JP2022500966A - Efficient coding of conversion factors used or suitable for combination with dependent scalar quantization - Google Patents

Abstract

Achieving more efficient coding of the coefficients of the transform block by using dependent quantization and context-adaptive entropy coding, or even if the use of dependent quantization is combined with the use of context-adaptive entropy coding, more The concept of achieving the coding of the coefficients of the conversion block is presented so as to allow efficient coding. [Selection diagram] FIG. 7

Description

The present application relates to conversion factor level coding such as encoding an image or video.

Encoders must compromise when setting the quantization parameters. If the quantization is coarse, the bit rate is lowered, but the quantization distortion is large, and if the quantization is fine, the distortion is small, but the bit rate is increased. It is preferable to have the concept of increasing coding efficiency for a given domain of available quantization level. One such possibility is the use of dependent quantization, where the quantization is constantly adapted depending on the previously quantized and encoded data. However, dependencies in quantization also create problems such as increased coding complexity, which affect the interrelationships between the data items that are quantized and encoded, and the individual syntax. Accumulate reduced information to perform context modeling so as to affect the availability of information about context derivation for encoding elements.

Achieve more efficient coding of transform block coefficients by using dependent quantization and context-adaptive entropy coding, or even more efficient when the use of dependent quantization is combined with the use of context-adaptive entropy coding. It is preferable to have the concept of achieving the coding of the coefficients of the conversion block so as to enable the coding.

It is an object of the present invention to provide such a concept for encoding a block of conversion coefficients.

This object is achieved by the subject matter of the independent claims of the present application.

An advantageous embodiment is the subject of the dependent claim. Preferred embodiments of the present application will be described with reference to the following drawings.

FIG. 1 is an example of an image encoder that may be embodied in order to operate according to any of the embodiments described below or to incorporate functionality according to the embodiments described herein. A block diagram of a typical video encoder is shown. FIG. 2 shows a block diagram of (a) a conversion encoder and (b) a conversion decoder showing a basic approach to block-based transform coding. FIG. 3 shows a histogram of the distribution showing a uniformly reconstructed quantizer. FIG. 4 shows a schematic diagram of (a) a conversion block subdivided into subblocks and (b) a subblock to illustrate an example for scanning conversion factor levels, where typically. , H. 265 | Used in MPEG-H HEVC; in particular, (a) indicates the division from the 16x16 conversion block into 4x4 subblocks and the coding order of the subblocks, and (b) is within the 4x4 subblocks. The coding order of the conversion coefficient level of is shown. Typically, subdivisions may be used in embodiments of the present application for the path of coefficients in decoding their flags and residues and the state transitions in dequantizing them. FIG. 5 shows a schematic representation of the multidimensional output space expanded by one axis for each conversion factor and the position of the reconstruction vector acceptable for the simple case of the two conversion factors: (a) Independent scalar. Quantization, (b) Examples of dependent scalar quantization. FIG. 6 shows a block diagram of a conversion decoder using dependent scalar quantization, thereby forming an embodiment of the media decoder according to the present application. Modifications to conventional transform coding (using an independent scalar quantizer) can be derived by comparison with FIG. 2b. Similarly, embodiments for encoding transformation blocks using dependent scalar quantization can be obtained by modifying the encoder as in FIG. 2a. FIG. 7 is a schematic diagram showing an embodiment of two sets of reconstruction level dependent quantizations that are completely determined by a single quantization step size Δ, and the two sets of available reconstruction levels are It is highlighted in set 0 (overline) and set 1 (underline). An example of a quantization index showing the reconstruction level in a set is given by the number below the circle. Hollow circles and filled circles indicate two different subsets within the set of reconstruction levels; even if the subsets are used to determine the set of reconstruction levels for the next conversion factor in the reconstruction order. good. Both sets contain reconstruction levels equal to zero, but are otherwise relatively prime; both sets are symmetric about zero. FIG. 8 shows a pseudo code exemplifying an example of the conversion factor reconstruction process. k represents an index to identify a reconstruction order of the current transform coefficients, the quantization indices for the current transform coefficients indicated by the level [k], the quantization step size delta _k to apply to the current transform coefficients quant_step_size indicated by [k], trec [k] represents the value of the transform coefficients _t'k reconstructed. The variable setId [k] specifies the set of reconstruction levels to apply to the current conversion factor. It is determined in the reconstruction order based on the previous conversion factors; the possible values of setId [k] are 0 and 1. The variable n identifies an integer factor of the quantization step size; it is given by a selected set of reconstruction levels (ie, the value of setId [k]) and the transmitted quantization index level [k]. Be done. FIG. 9 shows a pseudo code exemplifying another implementation of the pseudo code in FIG. The main change is that multiplication with the quantization step is represented using an integer implementation that uses scale and shift parameters. Typically, the shift parameter (represented by shift) is constant for the conversion block and only the scale parameter (given by scale [k]) may depend on the position of the conversion factor. The variable add represents the rounding offset, which is typically set equal to add = (1 << (shift-1)). Δ _k is the nominal quantization step for the conversion factor, and the parameters shift and scale [k] are selected to have _{Δ k} ≈ scale [k] · 2- ^shift. FIG. 10 shows a pseudo code showing an example of a conversion factor reconstruction process for a conversion block. The array level represents the conversion factor level (quantization index) sent to the conversion block, and the array trec represents the corresponding reconstructed conversion factor. The two-dimensional table state_trans_table identifies the state transition table, and the table setld identifies the quantization set associated with the state. FIG. 11 shows a schematic diagram showing state transitions in dependent scalar quantization as a trellis structure. The presence of a horizontal position represents a conversion factor with a different reconstruction order. The vertical axis represents different possible states in the dependent quantization and reconstruction process. The connections shown identify the paths available between the states for different conversion factors. FIG. 12a shows a schematic diagram of a conversion block for exemplifying the signaling of the position of the first non-zero quantized index in the coding sequence whose position is indicated by back filling. In addition to the position of the first nonzero conversion factor, only bins for the shaded coefficients are sent and the white marked coefficients are estimated to be equal to zero. FIG. 12b shows a schematic of the transformation block and shows a template used to select a probabilistic model. The black squares identify the current scan location and the shaded squares represent the local neighborhood used to derive the context model. FIG. 13-1 shows a pseudo code according to the first embodiment that encodes the conversion factor block. FIG. 13-2 shows the pseudo code according to the first embodiment that encodes the conversion factor block. FIG. 14 is a schematic diagram showing the representation of the quantized index of the conversion factor according to the embodiment of FIG. 13 by recursively dividing the value domain of the quantized index into two. FIG. 15 is a schematic diagram showing the various paths in the decoding example of FIG. 13 showing how the conversion coefficients are traversed and which flags or residues are encoded by the paths according to the example of FIG. FIG. 16-1 shows a pseudo code for explaining a second embodiment for encoding a conversion factor block. FIG. 16-2 shows a pseudo code for explaining a second embodiment for encoding a conversion factor block. FIG. 17 is a schematic diagram showing the representation of the quantized index of coefficients according to the embodiment of FIG. FIG. 18-1 shows a pseudo code showing a third embodiment for encoding a conversion factor block. FIG. 18-2 shows a pseudo code showing a third embodiment for encoding a conversion factor block. FIG. 19-1 shows a pseudo code showing a fourth embodiment for encoding a conversion factor block. FIG. 19-2 shows a pseudo code showing a fourth embodiment for encoding a conversion factor block.

According to the embodiments described below, transform coding is used to transform a set of samples. Dependent quantization is used to quantize the resulting transformation coefficients, with entropy coding, or context-adaptive arithmetic coding, of the resulting quantization index. On the decoder side, the set of reconstructed samples is obtained by corresponding to the decoding of the quantized index and the dependent reconstruction of the transformation coefficients, and the inverse transformation yields the samples. The sample can be part of an image or video and can describe a particular image block. Of course, there are other possibilities as well. The following embodiments are primarily directed to Rossy coding of blocks of prediction error samples in image and video codecs, but embodiments can also be applied to other areas of Rossy coding. In particular, there are no restrictions on the set of samples that form the rectangular block, and there are no restrictions on the set of samples that represent the prediction error sample (ie, the difference between the original and the prediction signal).

All modern video codecs, such as international video coding standards, H.D. 264 | MPEG-4 AVC and H.M. 265 | MPEG-H HEVC and the like follow the basic approach of hybrid video coding. The video image is divided into blocks, the block samples are predicted using intra-picture prediction or inter-prediction, and the resulting prediction error signal (the difference between the original sample and the prediction signal sample) is transform-coded. Encoded using.

FIG. 1 shows a simplified block diagram of a typical modern video encoder. The video images in a video sequence are encoded in a particular order, called the coding order. The coding order of the images may differ from the capture and display order. For actual coding, each video image is divided into blocks. The block contains a sample of the rectangular area of a particular color component. The entity of a block of all color components corresponding to the same rectangular area is often referred to as a unit. H. 265 | In MPEG-H HEVC, depending on the purpose of block division, it is distinguished between coded tree block (CTB), coded block (CB), predictive block (PB) and conversion block (TB). .. The related units are referred to as a coding tree unit (CTU), a coding unit (CU), a prediction unit (PU), and a conversion unit (TU).

Typically, the video image is first divided into fixed size units (ie, fixed size blocks aligned for all color components). H. 265 | In MPEG-H HEVC, these fixed size units are called Coded Tree Units (CTUs). Each CTU may be further divided into a plurality of coding units (CUs). A coding unit is an entity for which a coding mode (eg, intra- or inter-picture coding) is selected. H. 265 | In MPEG-H HEVC, the decomposition of CTU into one or more CUs is identified by a quadtree (QT) syntax and transmitted as part of a bitstream. The CU of the CTU is processed in the so-called z-scan order. That is, the four blocks resulting from the split are processed in raster scan order, and if any of the blocks are further split, the corresponding four blocks are processed before the next block at the higher split level is processed. Blocks (including smaller blocks included) are processed.

If the CU is encoded in the intra-encoding mode, an intra-prediction mode for the luminance signal and, if the video signal contains color-difference components, another intra-prediction mode for the color-difference signal is transmitted. .. ITU-T H. 265 | In MPEG-H HEVC, if the CU size is equal to the minimum CU size (as signaled by the sequence parameter set), the luminance block is divided into four equally sized blocks, in which case these blocks. A separate luminance intra-prediction mode is transmitted for each of the above. The actual intra-prediction and coding is based on the conversion block. For each transform block of the intra-picture coding CU, the prediction signal is derived using an already reconstructed sample of the same color component. The algorithm used to generate the prediction signal for the conversion block is determined by the transmitted intra prediction mode.

The CU encoded in the interpicture coding mode may be further divided into a plurality of prediction units (PUs). The prediction unit is an entity of luminance and, in the case of color video, two related color difference blocks (covering the same picture area), and a single set of prediction parameters is used. The CU may be encoded as a single prediction unit, or it may be divided into two non-square (symmetrical and asymmetric divisions are supported) or four square prediction units. For each PU, an individual set of motion parameters is transmitted. The motion parameters for each set are the number of motion hypotheses (1 or 2 in H.265 | MPEG-H HEVC) and for each motion hypothesis shown in the list of reference pictures via the reference picture index. Includes) and associated motion vectors. Furthermore, H. 265 | MPEG-H HEVC provides a so-called merge mode in which motion parameters are not explicitly transmitted and are derived based on the motion parameters of spatially or temporally neighboring blocks. When the CU or PU is encoded in merge mode, only the index of the list of motion parameter candidates (this list is derived using motion data of spatially and temporally neighboring blocks) is transmitted. The index completely determines the set of motion parameters used. The prediction signal for the intercoded PU is formed by motion compensation prediction. For each motion hypothesis (specified by the reference picture and motion vector), the prediction signal is formed by the displaced blocks in the identified reference picture, and the displacement with respect to the current PU is specified by the motion vector. Displacement is typically specified by subsample accuracy (in H.265 | MPEG-H HEVC, the motion vector has a quarter luminance sample accuracy). For non-integer motion vectors, inserting a reconstructed reference picture (typically using a separable FIR filter) produces a predictive signal. The final prediction signal of the PU with many hypothesis predictions is formed by the weighted sum of the prediction signals for each motion hypothesis. Typically, the same set of motion parameters is used for the luminance and color difference blocks of the PU. High-order motion models (eg, affine motion models) can be used, even though modern video coding standards use translational displacement vectors to identify the motion of the current region (sample block) with respect to the reference picture. It is possible. In that case, additional motion parameters must be sent for the motion hypothesis.

For both intra-picture and inter-picture coding CU, the prediction error signal (also called the residual signal) is typically transmitted via transform coding. H. In 265 | MPEG-H HEVC, the block of luminance residual sample of CU and the block of color difference residual sample (if any) are divided into conversion blocks (TB). The division of the CU into conversion blocks is indicated by the quadtree syntax and is also called the residual quadtree (RQT). The resulting transform block is coded using transform coding: a 2d transform is applied to the block of residual samples and the resulting transform coefficients are quantized using independent scalar quantization, resulting in The resulting transform coefficient level (quantization index) is entropy-coded. For P and B slices, skip_flag is transmitted at the start of the CU syntax. If this flag is equal to 1, the corresponding CU indicates that it consists of a single prediction unit encoded in merge mode (ie, merge_flag is estimated to be equal to 1) and all conversion factors are 0. Indicates equality (ie, the reconstruction signal is equal to the prediction signal). In that case, only merge_idx is transmitted in addition to skip_flag. If skip_flag is equal to 0, the predictive mode (inter or intra) is signaled, followed by the syntactic features described above.

The picture must be completely reconstructed in the encoder, as the already encoded picture may be used for motion compensation prediction of the block in subsequent pictures. The reconstructed prediction error signal of the block (obtained by reconstructing the conversion factor given the quantization index and inverse transformation) is added to the corresponding prediction signal and the result is buffered for the current picture. Written. After all blocks of the picture have been reconstructed, one or more in-loop filters can be applied (eg, deblocking filters and sample adaptive offset filters). The final reconstructed picture is then stored in the decoded picture buffer.

The embodiments described below present concepts for encoding conversion factor blocks, such as those relating to prediction error. The concept is applicable to both intra-picture and inter-picture coding blocks. It can also be applied to transform coding of a non-rectangular sample portion. In contrast to traditional transform coding, transform coefficients are not quantized independently. Rather, they are quantized using dependent quantization. According to dependent quantization, the set of reconstruction levels available for a particular transformation factor depends on the quantization index selected for the other transformation coefficients.

All major video coding standards (including the latest standard H.265 | MPEG-H HEVC) utilize the concept of transform coding for coding blocks of prediction error samples. The block prediction error sample represents the difference between the original signal sample and the prediction signal sample for the block. The prediction signal can be derived by intra-picture prediction (in which case a sample prediction signal for the current block is derived based on an already reconstructed sample of neighboring blocks in the same picture) or interpicture. It is obtained by prediction (in which case a sample of the prediction signal is derived based on a sample of the already reconstructed picture). A sample of the original prediction error signal is obtained by subtracting the value of the sample of the prediction signal from the sample value of the original signal for the current block.

Transform coding of the sample block consists of linear transformation, scalar quantization and entropy coding of the quantization index. On the encoder side (see FIG. 2a), the N × M blocks of the original sample are transformed using the linear analytical transformation A. The result is an N × M block of conversion factors. The conversion factor t _k represents the original prediction error sample in different signal spaces (or different coordinate systems). The NxM conversion factor is quantized using an NxM independent scalar quantizer. Each conversion factor t _k is mapped to the quantization index q _k and is also called the conversion factor level. The obtained quantization index q _k is entropy-coded and written to a bitstream.

On the decoder side shown in FIG. 2b, the conversion factor level q _k is decoded from the received bitstream. Each conversion factor level q _k is mapped to the reconstructed conversion factor t ′ _k. The N × M blocks of the reconstructed sample are obtained by transforming the blocks of the reconstructed transformation coefficients using the linear synthetic transformation B.

For a typical prediction error signal, the transformation has the effect that the signal energy is concentrated on a small number of conversion coefficients. Compared to the original prediction error sample, the resulting statistical dependence between conversion coefficients is reduced.

The latest video coding standards use the separable discrete cosine transform (Type II) or its integer approximation. However, the transformation can be easily replaced without changing other aspects of the transform coding system. Examples of improvements proposed in the literature or standard documentation include:

● Use of Discrete Cosine Transform (DST) for intra-picture prediction blocks (possibly dependent on intra-picture prediction mode and / or block size). In addition, H. Note that 265 | MPEG-H HEVC already contains DST for intra-picture prediction 4x4 conversion blocks.
● Switch conversion: The encoder selects the conversion that is actually used from the predefined set of conversions. The set of available conversions is known for both encoders and decoders and can be efficiently signaled using an index on the list of available conversions. Their ordering in the set and list of available transformations can depend on other coding parameters for the block, such as the selected intra-prediction mode. In special cases, the transformation used is completely determined by encoding the parameters as in intra-prediction mode, so there is no need to send a syntax element that identifies the transformation.
● Non-separable conversion: The conversion used in encoders and decoders represents non-separable conversion. Note that the concept of transition transformations may include one or more non-separable transformations. For complex reasons, the use of non-separable conversions can be limited to specific block sizes.
● Multi-level conversion: The actual conversion consists of two or more conversion stages. The first conversion stage can consist of separable transformations with low computational complexity. Then, in the second stage, a subset of the resulting transformation coefficients are further transformed using non-separable transformations. The two-stage approach has the advantage that more complex non-separable transformations are applied to a smaller number of samples compared to non-separable transformations for the entire transformation block. The concept of multi-level transformation can be efficiently combined with the concept of switching transformation.

The conversion factor is quantized using a scalar quantizer. As a result of the quantization, the set of acceptable values for the conversion coefficients is reduced. In other words, the conversion factors are mapped to so-called additable sets of reconstruction levels (actually, a finite set). The set of reconstruction levels represents the appropriate subset of the set of possible conversion coefficient values. To simplify the following entropy coding, the acceptable reconstruction level is represented by a quantization index (also called the conversion factor level) and is transmitted as part of the bitstream. On the decoder side, the quantized index (conversion factor level) is mapped to the reconstructed conversion factor. Possible values for the reconstructed conversion factor correspond to a set of reconstructed levels. On the encoder side, the result of scalar quantization is a block at the conversion factor level (quantization index).

In this context, the term "independent scalar quantization" means that given a quantization index q for any conversion factor, the associated reconstructed conversion factor t'is all quantization indexes for other conversion coefficients. It shows the characteristic that it can be determined independently of.

H. 262 | Older video coding standards such as MPEG-2 video also have a distance between the reconstruction level zero and the first non-zero reconstruction level compared to the nominal quantization step size (eg, nominal quantization step). Identify modified URQs that are increased (up to three-half of size Δ).

The slice QP is typically transmitted within the slice header. In general, it is possible to modify the quantization parameter QP based on the block. A DQP (Delta Quantization Parameter) can be transmitted for that purpose. The quantization parameters used are determined by the transmitted DQP and the predicted QP value and are derived using the QP of the already encoded (typically nearby) block.

The main purpose of the quantization weight matrix is to provide the possibility of introducing quantization noise in a perceptually meaningful way. By using the appropriate weighting matrix, the spatial contrast sensitivity of human vision can be utilized to achieve a good trade-off between bit rate and subjective reconstruction quality. Nevertheless, many encoders use so-called flat quantization matrices, which can be transmitted efficiently using high-level syntax elements. In this case, the same quantization step size Δ is used for all conversion coefficients in the block. Therefore, the quantization step size is completely specified by the quantization parameter QP.

Blocks at the conversion factor level (quantization index for conversion factors) are entropy-coded (ie, transmitted in a lossless manner as part of the bitstream). Since linear transformations can only reduce linear dependencies, entropy coding at the transformation factor level typically takes advantage of the non-linear dependencies that remain between the transformation factor levels within the block for efficient coding. Designed to be able to. A well-known example is run-level coding in MPEG-2 video, H.M. Run-level-last coding in 263 and MPEG-4 video, H.M. 264 | Context Adaptable Variable Length Coding (CAVLC) in MPEG-4 AVC and H.M. 264 | MPEG-4 AVC and H.M. 265 | Context-adaptive binary arithmetic coding (CABAC) in MPEG-H HEVC.

The latest video coding standard H. 265 | MPEG-H The CABAC specified by HEVC follows a general concept that can be applied to a wide variety of conversion block sizes. Conversion blocks larger than the 4x4 sample are divided into 4x4 subblocks. The splits are shown in FIGS. 4a and 4b as an example of a 16x16 conversion block. The coding order of the 4x4 subblocks shown in FIG. 4a, as well as the coding order of the conversion factor levels within the subblocks shown in FIG. 4b, is generally specified by the inverse diagonal scan shown in the figure. For certain intra-picture prediction blocks, a horizontal or vertical scan pattern is used (depending on the actual intra-prediction mode). The coding sequence always starts at the high frequency position.

H. In 265 | MPEG-H HEVC, conversion factor levels are transmitted based on 4x4 subblocks. Lossless coding at the conversion factor level involves the following steps:

1. 1. The syntax element coded_block_flag is transmitted to signal whether a nonzero conversion factor level is present in the conversion block. If coded_block_flag is equal to 0, further data is not encoded due to the conversion block.
2. 2. The x and y coordinates of the first nonzero conversion factor level in the coding order (eg, the inverse diagonal scan order in the block direction shown in FIG. 4) are transmitted. The transmission of coordinates is divided into prefix and suffix parts. The standard uses the syntax elements last_sig_coeff_x_prefix, last_sig_coeff_y_prefix, last_sig_coeff_x_suffix and last_sig_coeff_x_suffix.
3. 3. Starting with the 4x4 subblock containing the first nonzero conversion factor level in the coding order, the 4x4 subblocks are processed in the coding order and the subblock coding involves the following major steps:
a. A syntax element coded_sub_block_flag is transmitted, which indicates whether the subblock contains a nonzero conversion factor level. For the first and last 4x4 subblocks (ie, the subblock containing the first nonzero conversion factor level or DC level), this flag is not transmitted and is estimated to be equal to 1.
b. If all conversion factor levels in a subblock with coded_sub_block_flag are equal to 1, the syntax element significant_coeff_flag indicates whether the corresponding conversion factor level is not equal to zero. This flag is only sent if its value cannot be estimated based on the data already sent. In particular, this flag is not sent for the first significant scan position (specified by the sent x and y coordinates), and the DC factor is a different subblock (in the coding order) than the first non-zero factor. If all other significant_coordinate_flags for the last subblock are equal to zero, then no transmission is made for the DC factor.
c. If the first eight conversion factor levels with significant_coeff_flag are equal to 1 (if any), the flag coeff_abs_level_greeter1_flag is transmitted. It indicates whether the absolute value of the conversion factor level is greater than 1.
d. If the first conversion factor with coeff_abs_level_greeter1_flag is equal to 1 (if any), the flag coeff_abs_level_greeter2_flag is transmitted. It indicates whether the absolute value of the conversion factor level is greater than 2.
e. If all levels with significant_coeff_flag are equal to 1 (exceptions are described below), the syntax element coeff_sign_flag is transmitted to identify the sign of the conversion factor level.
f. If the absolute value is equal to zero for all conversion factor levels that are not already fully specified by the values of significant_coeff_flag, coeff_abs_level_greeter1_flag and coeff_abs_level_greeter2_flag (specific for any of the transmitted flags), the absolute value is full. The remainder of is transmitted using the multi-level syntax element coeff_abs_level_remaining.

H. 265 | In MPEG-H HEVC, all syntax elements are encoded using context-adaptive binary arithmetic coding (CABAC). All non-binary syntax elements are first mapped to a series of binary decisions, also known as bins. The resulting bin sequence is encoded using binary arithmetic coding. For that purpose, each bin is associated with a probability model (binary probability mass function), also known as the context. For most bins, the context represents an adaptive probability model, which means that the associated binary probability mass function is updated based on the actual encoded bin value. Conditional probabilities can be utilized by switching the context of a particular bin based on the data already sent. CABAC also includes a so-called bypass mode, in which a fixed probability mass function (0.5, 0.5) is used.

The context chosen for coding coded_sub_block_flag depends on the value of coded_sub_block_flag for the already encoded neighborhood subblocks. The context for significant_coeff_flag is selected based on the scan position (x and y coordinates) in the subblock, the size of the transform block and the value of coded_sub_block_flag in the nearby subblock. For the flags coeff_abs_level_greeter1_flag and coeff_abs_level_greater2_flag, the context selection depends on whether the current subblock contains a DC factor and whether the coeff_abs_level_be_flag equal to 1 depends on the nearby subblock. For coeff_abs_level_greeter1_flag, it further depends on the number and value of coeff_abs_level_greeter1_flag already encoded for the subblock.

The code coeff_sign_flag and the absolute residual coeff_abs_level_remaining are encoded in the bypass mode of the binary arithmetic code. When mapping coeff_abs_level_remaining to a bin sequence (binary determination), an adaptive binarization scheme is used. Binarization is controlled by a single parameter and is fitted to the subblock based on the already encoded values.

H. 265 | MPEG-H HEVC also includes a so-called code data hiding mode, omitting the transmission of the code for the last nonzero level in the subblock (under certain conditions). Instead, the sign for this level is embedded in the parity of the sum of the absolute values for the level of the corresponding subblock. Note that the encoder must take this aspect into account when determining the appropriate conversion factor level.

The video coding standard only identifies the bitstream syntax and the reconstruction process. The encoder has many degrees of freedom when considering transform coding for a given block and given quantization step size of the original prediction error sample. _{Given a quantization index q k} for the transformation block, entropy coding must follow a uniquely defined algorithm (ie, constructing an arithmetic code word) for writing data to the bitstream. _{However, the encoder algorithm for obtaining the quantization index q k} given the original block of the prediction error sample is outside the scope of the video coding standard. Further, the encoder has a degree of freedom in selecting the quantization parameter QP on a block-by-block basis. In the following description, it is assumed that the quantization parameter QP and the quantization weight matrix are given. Therefore, the quantization step size of each transmutation coefficient is known. Further assume that the encoder performs an analytical transformation that is the inverse (or vice versa) of the specified synthetic transformation to obtain the original transformation factor t _k. Even under these conditions, the encoder has the freedom to choose the quantization index q _{k for each original conversion factor t k.} Since the choice of conversion factor level determines both distortion (or reconstruction / approximation quality) and bit rate, the quantization algorithm used has a substantial effect on the rate-distortion performance of the generated bitstream.

The modified concept for transform coding is that the transform coefficients are not independently quantized and reconstructed. Instead, the acceptable reconstruction level of the conversion factor depends on the quantization index selected for the preceding conversion factor in the reconstruction order. The concept of dependent scalar quantization, combined with modified entropy coding, relies on a set of acceptable reconstruction levels for the choice of probabilistic model (or, alternative, the choice of codeword table) for the transformation coefficients. ..

Dependent scalar quantization of the transformation factor is the distance between the input vector given the transformation factor and the nearest available reconstruction vector for a given average number of reconstruction vectors per N-dimensional unit volume. It has the effect of reducing the expected value of. As a result, the average distortion between the input vector of the transformation factor and the vector reconstruction transformation coefficient can be reduced for a given average number of bits. In vector quantization, this effect is called the space-filling gain. Dependent scalar quantization can be used for transform blocks to take advantage of most of the potential spatial fill gains for high-dimensional vector quantization. And, in contrast to vector quantization, the complexity of the implementation of the reconstruction process (or decoding process) is comparable to conventional transform coding with an independent scalar quantizer.

Like conventional transform coding, transform coding according to the embodiments outlined herein further includes analytic transformation, quantization algorithms and entropy coding. As the analytical transformation, the inverse of the synthetic transformation (or vice versa) is typically used, and entropy coding usually uniquely identifies a given entropy decoding process. However, as with traditional transform coding, there are many degrees of freedom in choosing a quantized index given the original transform coefficients.

Dependent quantization of transformation coefficients is based on the notion that the set of reconstruction levels available for transformation coefficients depends on the selected quantization index of the transformation coefficients that precede them in the reconstruction order (within the same transformation block). Point to.

Multiple sets of reconstruction levels are predefined, and one of the predefined sets is selected to reconstruct the current conversion coefficients based on the quantization index of the conversion coefficients that precede in the coding order. To.

In one embodiment, dependent scalar quantization for transformation coefficients uses exactly two different sets of reconstruction levels. And all reconstruction levels of the two sets for the conversion factor t _{k are integer multiples of the quantization step size Δ k} (at least partially determined by the block-based quantization parameters) for this conversion factor. show. Note that the quantization step size Δ _k only represents the scaling factor for the acceptable reconstruction values in both sets. The same two sets of reconstruction levels are used for all transformation coefficients, except for the possible individual quantization step sizes Δ _{k (and individual scaling coefficients) for different transformation coefficients t k} within the transformation block. Will be done.

A more preferred configuration for the two sets of reconstruction levels is shown in FIG. The reconstruction level contained in the first quantization set (labeled as set 0 in the figure) represents an even integer multiple of the quantization step size. The second quantization set (labeled as set 1 in the figure) contains all odd integer multiples of the quantization step size and also contains a reconstruction level equal to zero. Note that both reconstruction sets are almost zero and symmetric. Reconstruction levels equal to zero are included in both reconstruction sets, otherwise the reconstruction sets are relatively prime. The combination of both reconstruction sets contains all integer multiples of the quantization step size.

The reconstruction level selected by the encoder from the acceptable reconstruction levels must be indicated or transmitted within the bitstream. Like traditional independent scalar quantization, this can be achieved using the so-called quantization index, also known as the conversion factor level. The quantization index (or transformation factor level) is an integer number that uniquely identifies the available reconstruction levels within the quantization set (ie, within the reconstruction level set). The quantized index is sent to the decoder (using entropy coding technology) as part of the bitstream. On the decoder side, the reconstructed conversion coefficients are the current set of reconstruction levels (determined by the preceding quantization index in the coding / reconstruction order) and the quantization index sent for the current conversion coefficients. Can be uniquely calculated based on.

The reconstruction level in FIG. 7 is labeled with the associated quantization index (the quantization index is given by the number below the circle representing the reconstruction level). Quantization indexes equal to 0 are assigned to reconstruction levels equal to 0. A quantization index equal to 1 is assigned to the minimum reconstruction level greater than 0, and a quantization index equal to 2 is assigned to the next reconstruction level greater than 0 (ie, a second minimum reconstruction level greater than 0). Such. That is, in other words, reconstruction levels greater than 0 are labeled with integer numbers greater than 0 (ie, having 1, 2, 3, etc.) in ascending order of their values. Similarly, the quantized index-1 is assigned to the maximum reconstruction level less than 0, the quantized index-2 is assigned to the next (ie, second largest) reconstruction level less than 0, and so on. That is, in other words, reconstruction levels less than 0 are labeled with integer numbers less than 0 (ie, -1, -2, -3, etc.) in descending order of their values.
The use of reconstruction levels, which represent integral multiples of the quantization step size, allows for computationally less complex algorithms for reconstruction of conversion coefficients on the decoder side. This is shown below based on the more preferred example of FIG. The first quantization set contains all even integer multiples of the quantization step size, and the second quantization set contains all odd integer multiples of the quantization step size and a reconstruction level equal to 0 (both quanta). Included in the conversion set) and. The conversion coefficient reconstruction process can be performed in the same manner as the algorithm specified in the pseudo code of FIG.

The other (simply superficial) change in FIG. 9 compared to FIG. 8 is that switching between two sets of reconstruction levels uses the ternary if-then-else operator (a? B: c). It is known from programming languages such as the C programming language.

In addition to the selection of the set of reconstruction levels described above, another task in dependent scalar quantization in transform coding is used to switch between the defined quantization sets (sets of reconstruction levels). It is an algorithm. The algorithm used determines the "compression density" that can be achieved in the N-dimensional space of the conversion factor (and also in the N-dimensional space of the subsequently reconstructed sample). Higher compression densities ultimately result in increased coding efficiency.

In a more preferred embodiment, the transition between the quantization sets (set 0 and set 1) is determined by the state variables. For the first conversion factor in the reconstruction order, the state variables are set equal to the predefined values. Typically, the predefined value is equal to zero. The state variables of the next conversion factor in the coding order are determined by the update process. The state of a particular conversion factor depends only on the state of the preceding conversion factor and the value of the preceding conversion factor in the reconstruction order.

The state variable may have four possible values (0,1,2,3). State variables, on the other hand, identify the quantization set used for the current conversion factor. Quantization set 0 is used only when and when the state variable is equal to 0 or 1, and quantization set 1 is used only when and when the state variable is equal to 2 or 3. State variables, on the other hand, also identify possible transitions between quantization sets.

For example, the state of a particular conversion factor may only depend on the binary function of the state of the preceding conversion factor and the value of the preceding conversion factor level in the reconstruction order. Binary functions are referred to below as paths. In a particularly preferred embodiment, the following state transition table is used, where "path" refers to the binary function at the conversion factor level that precedes it in the reconstruction order.

The concept of state transitions in dependent scalar quantization allows for a less complex implementation for the reconstruction of transformation coefficients in a decoder. A preferred example for the process of reconstructing the conversion coefficients of a single conversion block is shown in FIG. 10 and uses C-style pseudocode.

In the pseudo code of FIG. 10, the index k specifies the reconstruction order of the conversion coefficients. It should be noted that in the exemplary code, the index k is in descending order in the reconstruction order. The final conversion factor has an index equal to k = 0. The first index kstart identifies the reconstructed index (or, more precisely, the inverse reconstructed index) of the first reconstructed conversion factor. The variable kstart may be set equal to the number of conversion coefficients in the conversion block minus one, or (eg, transmitted in an entropy coding method to which the position of the first non-zero quantization index is applied). If) may be set equal to the index of the first non-zero quantization index in the coding / reconstruction order. In the latter case, all preceding conversion coefficients (with index k> kstart) are estimated to be equal to zero. The reconstruction process for each single conversion factor is the same as in the example of FIG. As in the example of FIG. 9, the quantized index is represented by level [k] and the associated reconstructed transformation is represented by trec [k]. State variables are represented by state. The one-dimensional table setId [] specifies the quantization set associated with different values of the state variables, and the two-dimensional table state_trans_table [] [] is the current state (first argument) and path (second argument). Argument) specifies the given state transition. As an example, the path can be given by the parity of the quantized index (in bits and using the operator &), but other concepts are possible. As another example, the path can specify whether the conversion factor is equal to or not equal to zero. Examples of tables in the C-style syntax are as follows (these tables are the same as Table 1 above).

setId [4] = {0, 0, 1, 1}
state_trans_table [4] [2] = {{0,2}, {2,0}, {1,3}, {3,1}}

Instead of using the table state_trans_table [] [] to determine the next state, you can use an arithmetic operation that produces the same result. Similarly, the table setld [] can also be implemented using arithmetic operations. Alternatively, the combination of the table and the sign function searched using the one-dimensional table setId [] can be implemented using arithmetic operations.

The main aspect of dependent scalar quantization is the existence of different sets of acceptable reconstruction levels (also called quantization sets) for the transformation coefficients. The quantization set for the current conversion factor is determined based on the value of the quantization index for the preceding conversion factor. Considering the example of FIG. 7 and comparing the two quantization sets, it is clear that the distance between the reconstruction level equal to 0 and the neighboring reconstruction level is greater in set 0 than in set 1. .. Therefore, if set 0 is used, the probability that the quantized index is equal to 0 is greater, and if set 1 is used, it is smaller. This effect may be utilized in entropy coding by switching the state-based probabilistic model used for the quantization set or more generally the current quantization index.

For proper switching of codeword tables or stochastic models, all preceding quantized index paths (binary functions of the quantized index) are the current quantized index (or the corresponding binary of the current quantized index). Note that the decision) must be known when entropy decoding.

The quantization index is H. 264 | MPEG-4 AVC or H.M. 265 | MPEG-H It may be encoded using the same binary arithmetic coding as HEVC. For that purpose, the non-binary quantization index is first mapped to a series of binary decisions (usually called bins).

Below are various examples of how, in what order, and in what context, the quantization index resulting from dependent quantization is binarized and arithmetically coded. Will be done. Here, the quantized index is transmitted as an absolute value and an absolute value larger than 0 as a sign. Although the sign is transmitted as a single bin, there are many possibilities for mapping absolute values to a series of binary decisions that reveal themselves in the examples described below. The following description first focuses on the coding order and binarization schemes, and thus presents various examples. Then different examples for context modeling are explained. The latter may be combined with the former embodiment related to the coding sequence and binarization scheme, but the former embodiment is not limited to the latter example.

Example 1
The following binary and non-binary syntax elements are sent:
● sig_flag: Specifies whether the absolute value of the conversion factor level is greater than 0.
● If sig_flag is equal to 1, gt1_flag: Specifies whether the absolute value of the conversion factor level is greater than 1.
● If gt1_flag is equal to 1, gt2_flag: Specifies whether the absolute value of the conversion factor level is greater than 1.
● If gt2_flag is equal to 1, reminder: a non-binary syntax element that specifies the absolute level remainder. This syntax element is transmitted in bypass mode of the arithmetic coding engine, for example using Golomb rice coding.
The current syntax element is not estimated to be equal to 0. On the decoder side, the absolute value of the conversion factor level is reconstructed as follows:
absLevel = sig_flag + gt1_flag + gt2_flag + reminder
Additional gtX_flag may be transmitted, gt2_flag may be omitted, or both gt1_flag and gt2_flag may be omitted. sig_flag and gtX_flag are coded using an adaptive context model.

Example 2
The following binary and non-binary syntax elements are sent:
● sig_flag: Specifies whether the absolute value of the conversion factor level is greater than 0.
● If sig_flag is equal to 1, gt1_flag: Specifies whether the absolute value of the conversion factor level is greater than 1.
● When gt1_flag is equal to 1 ○ par_flag: Specify the parity of the remainder of the absolute value of the conversion coefficient level (that is, the absolute value-2).
○ reminder: A non-binary syntax element that specifies an absolute level residue (ie, (absolute value -2-par_flag) / 2). This syntax element is transmitted in bypass mode of the arithmetic coding engine, for example using Golomb rice coding.
The current syntax element is not estimated to be equal to 0. On the decoder side, the absolute value of the conversion factor level is reconstructed as follows:
absLevel = sig_flag + gt1_flag + par_flag + 2 * reminder
An additional gtX_flag may be transmitted, or the gt1_flag may be omitted. As an example, instead of the above reminder, gt2_flag (specifies whether the absolute value is greater than 3) and modified reminder (ie, (absolute value -3-par_flag) / (if gt2_flag is equal to 1)). 2) can be transmitted. After that, the absolute value can be configured as follows.
absLevel = sig_flag + gt1_flag + par_flag + 2 * (gt2_flag + reminder)
The sig_flag, gtX_flag and par_flag are encoded using the adaptive context model.

Example 3
The following binary and non-binary syntax elements are sent:
● sig_flag: Specifies whether the absolute value of the conversion factor level is greater than 0.
● When sig_flag is equal to 1 ○ par_flag: Specify the parity of the remainder of the absolute value of the conversion coefficient level (that is, the absolute value -1).
○ gt1_flag: Specifies whether or not the residual of the absolute value of the conversion coefficient level (that is, (absolute value-1-par_flag) / 2) is larger than 0.
● If gt1_flag is equal to 1, gt2_flag: Specifies whether the residual absolute value of the conversion factor level (ie, (absolute value-1-par_flag) / 2) is greater than 1.
● If gt2_flag is equal to 1, reminder: a non-binary syntax element that specifies an absolute level residue (ie, (absolute value-1-par_flag) / 2-2). This syntax element is transmitted in bypass mode of the arithmetic coding engine, for example using Golomb rice coding.
The current syntax element is not estimated to be equal to 0. On the decoder side, the absolute value of the conversion factor level is reconstructed as follows:
absLevel = sig_flag + par_flag + 2 * (gt1_flag + gt2_flag + reminder)
An additional gtX_flag may be transmitted, or the gt2_flag may be omitted. The sig_flag, gtx_flag and par_flag are encoded using the adaptive context model.

Further binarization is possible.

The following examples are provided to show the interrelationships between binarization, bin / coefficient ordering, and context derivation for context modeling. In a particular example, the syntax for sending the quantized index of the transform block is whether the quantized index is equal to zero, or whether it is not equal to 0 (sig_flag introduced above). Includes the specified bin. The probabilistic model used to encode this bin may be selected from a set of two or more probabilistic models. The choice of probabilistic model used depends on the current state variable (state variable means the quantization set used). In this case, different sets of probability models may be used for all possible values of the state variables, or different sets of probability models may be used for each cluster (eg, state 0 or). A first set of probability models of 1, a second set of probability models of state 2 and a third set of probability models of state 3; or, instead, a first set of probability models of state 0 or 1. , A second set of probabilistic models of state 2 or 3).

The selected probabilistic model for other binary syntax elements (eg, gt1_flag or par_flag) can also depend on the value of the current state variable.

When dependent quantization of the transformation coefficient is combined with entropy coding, the choice of a probabilistic model for one or more bins of the binary representation of the quantization index (also known as the quantization level) is the state variable of the current quantization index. Dependence is an advantage. State variables are given by a quantized index (or a subset of bins representing the quantized index) for the conversion coefficients that precede in the coding and reconstruction order.

In particular, advantageously, the described selection of the probabilistic model is combined with one or more of the following entropy coding embodiments:

● Sending a flag for a transformation block, which specifies whether one of the quantization indexes for the transformation block is not equal to zero, or all the quantization indexes for the transformation block are equal to zero.

● Splitting the coefficients of a transform block within multiple subblocks (at least for transform blocks that exceed the predefined size given by the dimensions of the block or the number of samples included). This is schematically shown for the conversion block 10 in FIG. 12a, where the coefficient 12 of the block is subdivided into sub-blocks 14, which are exemplary here the coefficients of size 4 × 4. If the transform block is split into multiple subblocks 14, then for one or more subblocks a flag is sent (unless estimated based on already transmitted syntax elements) and the subblocks are non-zero quanta. Specifies whether to include the quantized index. Subblocks may be used to specify the coding order of the bins. For example, the coded bins can be divided into subblocks 14, and all bins in the subblock are encoded before any of the bins in the next subblock 14 are transmitted. However, the bin of a particular subblock 14 can be coded in multiple passes across the conversion factors within this subblock. For example, all bins that specify the absolute value of the quantized index for a subblock may be encoded before any code bin is encoded. Bins for absolute values can also be split into multiple paths, as described above.

● Transmission of the first nonzero position in the coding order. The location is shown in FIG. 12a and is shown in bold. It can be sent as x and y coordinates that specify the position of the transformation factor in the two-dimensional array, it can be sent as an index in scan order, or it can be sent by any other means. As shown in FIG. 12a, the transmitted position of the first non-zero quantization index (or conversion factor) in the coding order is all conversion coefficients 12 (FIG. 12a) that precede the coefficient identified in the coding order. (Marked in white in) specifies that it is estimated to be equal to zero. In addition, the data is marked at the specified position (marked in black / bold in FIG. 12a), i.e., the coefficient at the first position in the coding order, and the coefficient following this coefficient in the coding order (marked with diagonal lines in FIG. 12a). Will only be sent for). The example of FIG. 12a shows a 16x16 conversion block 10 with a 4x4 subblock 14; the coding sequence used is H.I. 265 | MPEG-H Diagonal scan in sub-block units specified by HEVC. It should be noted that the coding of the quantized index at the specified position (the first non-zero coefficient in the coding order) may be slightly modified. For example, if the binarization of the absolute value of the quantized index contains a bin that specifies whether the quantized index is not equal to 0, this bin does not send the quantized index at the specified position (the coefficient is 0). (It is already known that it is not equal to), instead, the bin is estimated to be equal to 1.

● Binarization of the absolute value of the quantized index includes an adaptively encoded bin that specifies whether the quantized index is not equal to zero. The probabilistic model (called the context) used to encode this bin is selected from a set of candidate probabilistic models. The probabilistic model of the selected candidate may be determined by the state variables of the current quantized index, and may also be determined by the quantized index already transmitted for the transformation block. In a preferred embodiment, the state variable determines a subset of the available probability models (also called the context set), and the values of the already coded quantization index are the probabilities used within this subset (context set). Determine the model.

In a preferred embodiment, the stochastic model used in the context set is the value of the already coded quantization index at the local neighborhood 52 of the current conversion factor 50, i.e. the bin is currently coded / Determined based on the value of the coefficient being decoded, the context for the same need is determined. An example of such a local neighborhood 52 is shown in FIG. 12b. In the figure, the current conversion factor 50 is marked in black and the local neighborhood 52 is marked with diagonal lines. In the following, it can be derived based on the value of the quantization index of the coefficient 51 of the neighborhood within the local neighborhood 52, and then can be used to select a probabilistic model of a predetermined context set. Some exemplary processes are listed.

In addition, other data available to the decoder can be used (either explicitly or in combination with the processes listed above) to derive a probabilistic model within a predetermined context set. Such data includes:
○ Current conversion coefficient position (x-coordinate, y-coordinate, diagonal number or any combination thereof)
○ Current block size (vertical size, horizontal size, number of samples or any combination thereof)
○ Aspect ratio of the current conversion block

● Binarization of the absolute value of the quantized index includes an adaptively encoded bin that specifies whether the absolute value of the quantized index is greater than 1. The probabilistic model (called the context) used to encode this bin is selected from a set of candidate probabilistic models. The selected probabilistic model is determined by the quantized index already sent to the transform block. One of the above methods can be used to select a probabilistic model (for bins that specify whether the quantized index is not equal to 0).

As already mentioned above, the coding order of the binarization bins of the binarized index with a factor of 12 affects the coding efficiency of block 10. For example, the probability model selected for at least one of the binary decisions (bins), typically sig_flag, depends on the value of the current state variable. And since the state variable is determined by the binary function path () at the preceding conversion factor level, sig_flag (or more generally, the binary syntax element whose stochastic model depends on the state variable) for the current conversion factor. The coding order of the bins must be arranged so that the path for all preceding conversion coefficients is known when encoding.

For example, all bins that specify the absolute value of the quantization index can be continuously encoded. That is, every bin (relative to the absolute value) of every preceding quantization index in the coding / reconstruction order is encoded before the first bin of the current quantization index. The code bin may or may not be coded in a separate second pass across the conversion factor (which may actually depend on the quantization set used). The sign bin of a subblock can be encoded after the bin for the absolute value of the subblock, but before any bin for the next subblock.

In another example, only a subset of bins that specify the absolute value of the quantization index are continuously encoded in the first pass over the conversion factor. However, these bins uniquely specify state variables. The remaining bins are encoded in one or more additional paths over the conversion factor. Assuming the path is specified by the parity of the quantized index, the parity bin is included in the first path over the conversion factor. The remaining bins may be sent with one or more additional paths. In other embodiments of the invention, similar concepts are used. For example, the number of unary bins can be changed or even adapted based on symbols already transmitted. Different paths can be used based on the subblock, in which case the bins of the subblock are encoded by multiple paths, but all bins of the subblock are sent by one of the following subblocks: Sent before it is done.

In the following, some examples are listed to encode the binary decision in multiple passes.

Example A:
This example uses the binarization of Example 3 above, where the path is given by parity.
● Path 1: sig_flag, par_flag, gt1_flag
● Pass 2: gt2_flag
● Pass 3: remainder
● Path 4: sig_flag, par_flag, gt1_flag

Example B:
This example uses the binarization of Example 3 above, where the path is given by parity.
● Path 1: sig_flag, par_flag
● Pass 2: gt1_flag
● Pass 3: gt2_flag
● Pass 4: remainder
● Path 5: sign bits

Example C:
This example uses the binarization of Example 1 above, where the path specifies whether the absolute value is greater than zero.
● Path 1: sig_flag
● Pass 2: gt1_flag
● Pass 3: gt2_flag
● Pass 4: remainder
● Path 5: sign bits

Example D:
This example uses the binarization of Example 2 above, where the path is given by parity.
● Path 1: sig_flag, gt1_flag, par_flag
● Pass 2: remainder
● Path 3: sign bits

Example E:
This example uses the binarization of Example 2 above with an additional gt2_flag and the path is given by parity.
● Path 1: sig_flag, gt1_flag, par_flag, gt2_flag
● Pass 2: remainder
● Path 3: sign bits
As a minor modification of this example, gt2_flag can also be sent on separate paths.

Another coding order or combination is binarized and the coding order is possible.

It is preferable to keep the number of context-coded bins (also known as positive-coded bins) as low as possible (without degrading performance) to allow implementation of high-throughput decoders. This can be achieved (similar to HEVC) by limiting the maximum number of specific bins. The rest of the information is encoded using the bypass mode of the arithmetic coding engine.
The methods described below for reducing the maximum number of context-encoding bins may be combined with one or more of the following embodiments already presented above:

● Multiple sets of reconstruction levels for the quantization of conversion coefficients. In particular, two sets: the first set contains all even integer multiples of the quantization step size, and the second set contains all odd integer multiples and zeros of the quantization step size.
(At least part of the conversion factor in the conversion block)

● The selected set of reconstruction levels depends on state variables. The state variable is set equal to 0 for the first coefficient in the reconstruction order. For all other coefficients, the following applies: The value of the state variable of the current conversion factor is determined by the binary function (path) of the value of the state variable for the preceding conversion factor level and the value of the preceding conversion factor level.

● Conversion factor levels are binarized and bins are entropy-coded using binary arithmetic coding. Binarization involves sig_flag and specifies whether the conversion factor level is not equal to zero. This flag is encoded using an adaptive probability model, and the selected probability model depends on the value of the state variable of the current conversion factor (and potentially other parameters).

In the following, a plurality of embodiments for reducing the number of context-coded bins for dependent scalar quantization will be described. In these embodiments, the worst-case decoding complexity is limited on the basis of subblocks. Typically, like HEVC, the larger conversion block is split into 4x4 subblocks and the following applies:

● The syntax of the conversion block contains a syntax element (eg coded_block_flag) and specifies whether or not there is a nonzero conversion factor level in the conversion block. If coded_block_flag is equal to 0, all conversion factor levels are equal to 0 and no further data is sent to the conversion block; otherwise (coded_block_flag is equal to 1), the following applies;

● The x and y coordinates of the first significant conversion factor in the scan order are transmitted (this is sometimes referred to as the last significance factor because the actual scan order specifies scans from high frequency to low frequency components);

● Scanning of conversion factors is based on subblocks (typically 4x4 subblocks); all conversion factor levels in a subblock are coded by any conversion factor level in any other subblock. Encoded before being encoded, the subblocks are processed in a predefined scan order, starting with the subblock containing the first significance factor in the scan order and ending with the subblock containing the DC factor.

● The syntax contains coded_subblock_flag, indicating whether the subblock contains a non-zero conversion factor level; the first and last subblocks in the scan order (ie, the subblock containing the first significance factor in the scan order, and DC. In the case of subblocks containing coefficients), this flag is not transmitted, but is presumed to be equal to 1; if coded_subblock_flag is transmitted, it is typically transmitted at the beginning of the subblock.

● For each subblock whose coded_subblock_flag is equal to 1, the conversion factor level is transmitted in multiple scan paths across the scan positions of the subblock.

The following embodiments apply to the conversion factor level coding for subblocks with coded_subblock_flag equal to 1. However, this embodiment is not limited to this case. It is also possible to apply embodiments to complete the conversion block (without a subblock structure). In this context, it is possible to use a subblock structure (as described above), but apply the worst-case complexity limits (as described below) to complete the conversion block. Is possible (instead of applying it to subblocks to limit it individually).

Embodiment 1
In the first embodiment, the conversion factor level is encoded by a plurality of scan passes. It has the following properties.
● The state machine for dependent quantization is driven by the parity of the transformation factor level, that is, the binary function path (level) returns the parity of its argument;
● The probability model of sig_flag in the first pass is selected based on the corresponding values of the state variables (and optionally other parameters available to the decoder, see above).
First pass: The first pass for the scan position sends the following context-coded bins:
● sig_flag indicates whether the conversion factor is not equal to 0; if sig_flag can be estimated to be equal to 1 (eg, it is explicitly signaled by the first significant scan position (x and y coordinates) in the conversion block. In the case of), sig_flag is not transmitted.
● If sig_flag is equal to 1 (encoded or estimated value), the following is additionally sent for the current scan position:
○ par_flag specifies the value obtained by subtracting 1 from the absolute value parity.
○ gt1_flag specifies whether or not the residue (given by absolute level -1-par_flag) / 2 is greater than 0.
● When the predefined maximum number of context-coded bins is reached, the first pass ends. MAX_REG_BINS is the maximum number of bins that can be transmitted on the first pass, and regBins represents the number of positively coded bins that are still available. Then the following applies:
○ regBins is initially set equally to MAX_REG_BINS;
○ After encoding any bin (sig_flag, gt1_flag, par_flag), regBins is decremented by 1. ○ After sending bins for the scan position (sig_flag, and gt1_flag, par_flag if sig_flag is equal to 1) If the number of bin regBins still available is less than 3 (ie, sig_flag, par_flag and gt1_flag cannot be sent to the next scan position), then the first scan pass ends.
Second pass: The second pass for the scan position sends the following context-coded bins:
● If gt1_flag at the scan position is equal to 1, gt2_flag is sent and specifies whether the residue (given by (absolute level -3-par_flag) / 2) is greater than 0.
● If a predefined maximum number of context-coded gt2_flags has been sent, the second pass ends. When the scan position where no data is transmitted in the first pass is reached (that is, no data is transmitted in the second pass for such a scan position), the second pass also ends.
Third pass: In the third pass with respect to the scan position, all sig_flag encoded in pass 1 with absolute level residuals (ie, data not already specified by the transmitted sig_flag, par_flag, gt1_flag and gt2_flag). Sent to the scan position of. The remainder of the non-binary syntax element is binarized using structured code (such as Golomb rice code) and the bins are encoded in the bypass mode of the arithmetic coding engine. The remainder is sent for the following scan positions:
● For all scan positions, gt2_flag equal to 1 is sent on the second pass:
For these scan positions, the residue of non-binary syntax elements sent specifies:
(Absolute value-5-par_flag) / 2
● For all scan positions, gt1_flag equal to 1 was sent in the first pass, but gt2_flag was not sent in the second pass:
For these scan positions, the residue of non-binary syntax elements sent specifies:
(Absolute value-3-par_flag) / 2
Fourth pass: In the fourth pass, the absolute levels for all scan positions where no data was transmitted in the first pass are encoded. The absolute level is first binarized using structured code, and the code used can rely on local activity measurements as well as the value of the current state variable. Bins are sent using the bypass mode of the arithmetic coding engine.
Fifth pass: Finally, in the fifth pass, the sign of all conversion factor levels not equal to 0 is transmitted. The code is transmitted in bypass mode of the arithmetic coding engine.

The advantage of the embodiments described is that the number of context-encoded bins is efficiently reduced compared to a version that is not constrained by the number of bins in the first and second passes. Coding and decoding of context-coded bins requires more complex implementations than bins encoded in bypass mode, thus reducing complexity.

The above description will be illustrated based on the pseudo code shown in FIG. FIG. 13 shows a method for decoding a block of conversion coefficients according to the embodiment described above, wherein the corresponding coding embodiment is easily derived from it by replacing all "decodes" with "encodes". can do.

The pseudo code shown in FIG. 13 shows the coding / decoding process of the conversion factor level in the subblock 14. It is illustrated from the perspective of the decoder. Decoded from the data stream, to pass 60 ₁ to scan according to the position 12 the scan order of transform coefficients of the block 10 are performed in 60 ₅ sequences. Binarization is used, i.e. flags / bins are used to define the quantization index of the coefficients, and the distribution of flags and residues in the coding / decoding path is modified in the embodiments described below. Therefore, the description of FIG. 13 concentrates on providing an overview or schematic description that also applies to the embodiments described below.

The basic possibilities scan order paths, FIG. 12a, have been described above with respect to b, are shown by way of example at 62 in FIG. 12b, to pass 60 ₁ 60 ₅ all transform blocks 10 It is not necessary to scan position 12 of the conversion factor, but keep in mind that they use all scan sequences 62; flags for some of the flag types are the same path as described with respect to FIG. May be sent in, but there are other possibilities.

The predefined values MAX_REG_BINS and MAX_GT2_BINS shown in FIG. 13 specify the maximum number of positively coded bins in each of _{paths 1 60 1} and 2 60 _2. The Boolean variable firstSubblock is the first in a coding order (within a conversion block) in which the current subblock is coded / decoded for block 10, such as the subblock containing the bold / black factor 12 in FIG. 12a. Specifies whether it is a subblock. firstSigScanIdx specifies the scan index corresponding to the position of the first significant conversion factor in the conversion block 10, that is, the position of the coefficient explicitly signaled at the start of the conversion block syntax. Reference numeral 64 will be used in the future to indicate the position. minSubblockScanIdx and maxSubblockScanIdx represent the minimum and maximum scan indexes for the current, i.e., currently decoded / coded subblock. Note that the first scan index, startScanIdx, where any data is transmitted to the current subblock 14, depends on whether the subblock contains the first significance factor in the scan order. In this case, the first scan path starts at the scan index corresponding to the first significant conversion factor 64; otherwise, the first scan path is like the lower left coefficient position in subblock 14. Starting at the minimum scan index of the subblock, or in other words, the scan sequence 62 is guided to the position farthest from the DC position 66. Again, FIG. 13 is an embodiment used for subblock unit coding, but the concept relates to encoding the coefficients en-block, or associating some of the embodiments described below with subblocks. It should be noted that while others can be easily modified to relate to the whole block 10.

In the sequence of the path 60 ₁ to 60 _4, context adaptive binary arithmetic coding / decoding, for example, in the embodiment 1 described presently, sig_flag, par_flag, each from a set of one or more flags types including gt1_flag and gt2_flag Used to encode / decode the selected flag or bin, variable length code is used to encode / decode the residual value. That is, variable-length codeword bins are encoded / decoded in the bypass mode of the binary arithmetic coding / decoding engine using a uniform non-adaptive probability model, with one compression for each bin. It becomes a rate. Therefore, each flag and each residual value is decoded for the position of the currently scanned conversion factor, as shown by 50 in FIG. 12b, respectively. In pseudocode, this current position is indicated by a parameter or index k.

If the residual value is encoded / decoded for the position 50 of the particular current scan conversion factor, then the residual value is the residual value if at least one flag is decoded for the position of the conversion factor currently being scanned. Uniquely from the value domain or from the initial value domain to the absolute value of the quantization index for the position of the currently scanned conversion factor if the flag has not been decoded for the position of the currently scanned conversion factor. show. The residual value is not coded / decoded for the position of these conversion factors, and the position of the conversion factor where one or more flags are coded / decoded already limits the value domain and only one absolute value. Please note that it includes. As in the sign, if no conversion factor is shown, it is the case of this embodiment, but the same is coded separately in bypass mode so that it is assumed that the modified embodiment is not necessarily required. It may be converted. In Figure 13, it has been separately shown to be encoded / decoded in the own path 60 ₅ with respect to any non-zero quantization indices, which can be changed to arrive at further embodiments.

Dependent quantization is used to continuously dequantize the quantized index of the positions of the conversion coefficients in the coded set of positions of the conversion coefficients. This process yields a reconstructed conversion factor for this set of conversion factor positions. For example, state transitions as outlined above can be used. It is quantized by using a state transition table or trellis diagram according to scan sequence 62, for example by making a selection for the position of the current conversion factor shown using the index k as shown in FIG. The index is uniquely encoded / decoded by the above concept, and the set of levels reconstructed from the set 73 of the plurality of reconstruction levels, i.e., set 0 and set 1 of FIG. 7, is in FIG. 7 by "state". Shown, the quantized index points to a set of reconstruction levels, i.e., the reconstruction coefficients are set equal to the reconstruction levels, based on the states that the state transitions assume for the position of the current transformation coefficients. By dequantizing the quantization index level [k] to the reconstruction level trec [k] 74, and with respect to the position of the current conversion factor, i.e. the position of the conversion factor following the current conversion factor in the scan order. It may be embodied by updating the state of the assumed state transition for what is currently being scanned during dependent quantization to generate the updated state 78. Update 76 is performed depending on the quantized index of the position of the current conversion factor, level [k] as shown by 80 in FIG. 10, where table 82 is used at the end. Similarly, the quantization using the selected level set is done on the encoder side.

As illustrated above, state transitions may be transitions between four different states corresponding to the four elements of the vector shown in FIG. Further, the update depends on the binary function 86, such as the parity function applied to the quantization index 80 of the position of the current conversion factor, with the first successor state and the second successor states 84 ₁ and 84 ₂ . It may be performed by determining the interval, the first successor state and the second successor state depend on the state of the position of the current conversion factor, as indicated by 88. Is shown. The encoder and decoder predetermined quantization step size, i.e. in Fig. 7 delta, displays the reconstructed level set in the FIG. 10, 2 ^Shift parameter, the information about the predetermined quantization step size , For example, transmitted in a data stream. Further, as shown in FIG. 7, each reconstruction level set has a predetermined quantization step size that is constant or valid for all reconstruction level sets for the position of the current transformation factor. It may be composed of an integral multiple of. Note that different step sizes may be used for different coefficients in one block 10 due to the scaling matrix described above. Of the plurality of reconstruction level sets, the number of reconstruction level sets may be 2, and the plurality of reconstruction level sets are the first reconstruction including zero and an even multiple of the predetermined quantization step size. It may include a level set, i.e. set 0, and a second reconstruction level set containing an odd multiple of a predetermined quantization step size.

So far, the description of FIG. 13 also applies to the embodiments described below. However, Embodiment 1 uses the following mechanism to limit the number of flags encoded using context adaptability. In particular, the particular path of a sequence of paths, namely the path 60 ₁ shown in FIG. 13, Sig_flag type flag, the first time meets predetermined position predetermined abort criteria according to the scan order in the first pass Only encoded / decoded up to-"to" should be understood herein as preceding and including positions, while "after [position 112]" position references refer to position 112. It should be understood to represent the position after the position 112 to be excluded. In Figure 13, not only the number of sig_flag is limited in this method, Par_flag, the number of gt2_flag in gt1_flag and path 60 ₂ in pass 60 ₁ is also limited. Note that the limit affects binarization: as soon as the abort criteria are met, each flag type defines a coefficient position following the position of the previous predetermined conversion factor in the scan order. Is no longer used. That is, a pre-determined flag type flag, i.e. subject to a limitation on the number of coded / decoded numbers, is relative to the position of the conversion factor preceding and including the position of the pre-determined conversion factor in the scan order. Only encoded / decoded. Thus, in Figure 13, about the path 60 _1, i.e. as soon as the criteria associated with MAX_REG_BINS are satisfied, for each of the encoded set of positions of the transform coefficients following the position of the predetermined transform coefficients in scan order , further the path sequence of the path, i.e. the path 60 ₃ in the case of FIG. 13, one of the residual value is encoded, the latter directly, i.e., each encoding / decoding the quantization index coefficient Any of the flags of the flag type used to uniquely indicate the absolute value of the quantization index for the position of each conversion factor in the initial value domain, without the preceding restrictions of the initial value domain.

14 and 15 are referenced in addition to FIG. 13 to illustrate the concepts presented earlier for limiting the number of flags encoded / decoded in a context adaptive manner. FIG. 14 shows the initial value domain for the absolute value of the quantized index of the conversion factor at 90. This initial value domain can contain all integer values between zero and any of the maximum values. The initial domain may be an interval that opens toward a larger number. The number of integer values in the initial value domain 90 does not necessarily have to be a power of two. In addition, FIG. 14 shows various flag types related to representing individual quantization indexes, i.e., to showing their absolute value. There is a sig_flag type that indicates whether the absolute value of a particular quantization index is zero. That is, sig_flag 92 divides the initial value domain 90 into two subparts, i.e. one contains only zeros and the other contains all other possible values. That is, as shown in the lower part of FIG. 14, when the latter is zero, sig_flag already uniquely indicates the absolute value of the quantized index. The non-zero values of the initial value domain 90 form the value domain 94, which value domain 94 is further subdivided by the flag type par_flag, i.e. one is an odd value and the other is an even value. Only if the latter is non-zero, par_flag96 needs to be present for a particular quantization index. par_flag 96 does not create uniqueness for one of the similarly bisected halves of the value domain 94. It shows half of the resulting (recursively defined) value domain, so the next flag, gt1_flag98, divides this resulting value domain into two after par_flag and further quantizes the index. When the value is odd, it indicates an odd non-zero value 100, and when the quantization index value is even, it indicates an even non-zero value 102. In particular, the dichotomy by gt1_flag98 is performed such that one portion simply contains the minimum odd value 100 of the value domain or the minimum nonzero even value 102 of the value domain, respectively. Other parts include all other values 100/102 for each domain. The latter of the rest of the value domain is further subdivided by the flag gt2_flag104 in the same way, i.e., where the minimum value represents one part and the other value represents the other part. As shown at the bottom of FIG. 14, this means that if the latter is zero, then sig_flag92 is simply encoded for the quantized index of a particular conversion factor, the latter having absolute values 1 and 2. When divided into the inclusion interval 106, sig_flag, par_flag and gt1_flag 92, 96 and 98 are encoded to represent a particular quantization index of a particular conversion factor and all flags 92, 96, 98 and 104. Is encoded to represent the absolute value of the quantized index of a particular conversion coefficient when divided into the value interval 108 immediately after containing the values 3 and 4, and additionally the absolute value is the initial value domain 90. It is encoded for the absolute value of the quantization index of a particular conversion coefficient in the remaining interval 110 of. Flag type flags 92, 96 and 98 are encoded in the first pass 60 _1. Flag 104 is encoded in the second pass 60 _2. These flags are encoded using context-adaptive arithmetic coding. However, the number of flags encoded in the path may be limited or may be limited by FIG. In the example of FIG. 13, the number of flag types of flags in the path 60 ₁ is limited to Max_rec_bins. In the path 60 ₁ Total encoded flag, without exceeding the number of coded / decoded maximum permitted flag was in the path 60 _1, if there is likely to be encoded in the path 60 ₁ Only , Flags of flag type 92, 96 and 98 are encoded for position 12 of the currently accessed conversion factor in the first path according to sequence 62. In Figure 15, shows that the position of the last transform coefficient that does not exceed the maximum number of permissible flag in the path 60 ₁ is 112. Similarly, the total number of encoded flag 104 in the path 60 _2, without exceeding the maximum number of allowed flag in the path 60 ₂ encoded / decoded, it is encoded in the path 60 ₂ Only if possible, flag 104 of the flag type is encoded for position 12 of the currently accessed conversion factor in the second path according to sequence 62. In Figure 15, it is shown that the position of the last transform coefficient that does not exceed the maximum number of permissible flag in the path 60 ₂ is 116.

FIG. 15 shows the coding of the conversion coefficients or their quantized indexes with their respective subblocks 14, but as already shown above, the embodiment of FIG. 13 is blocked by all processes of FIG. 13 as a whole. As long as it applies to 10, it may be changed. Further, FIG. 15 shows the case where the coded set of conversion coefficients contains, for example, all the coefficients in the case of the subblock following the subblock in the scan order including the position 64 of the first nonzero conversion factor. .. Accordingly, the positions of all conversion factors shown in diagonal lines in FIG. 15 relate to the quantized index of the conversion factors represented to include flag types 92, 96 and 98. Therefore, the first pass 60 _1, these flags types of flags 92 and 96 and 98 are encoded with respect to the transform coefficients 12 to the position 112. For some transform coefficients 12 to the position 112, but simply sig_flag92 needs to be encoded, whereas, contains all of the other three flags types are encoded / decoded in the path 60 _1. Figure 15 is a data stream, indicating that comprises accordingly, the corresponding portion 114 these flags types of flags 92, 96 and 98 are encoded by the path 60 within _1. After position 112, nothing is encoded / decoded in the path 60 within _1. In the second pass 60 ₂ , according to the scan sequence 62, _{as long as there is a maximum number of gt2_flags that can be encoded between passes 60 2} , i.e., as long as the number of such flags does not exceed max_gt2_bins, the position of the conversion factor. Twelve is traversed again and such gt2_flag is encoded for the conversion factor indicated by gt1_flag98 that the absolute value of the corresponding quantization index is within the remaining value domain portion including intervals 108 and 118. FIG. 15 shows the positions 12 of all conversion factors up to the cross-hatched position 116 according to the scan sequence 62 and distinguishes these positions from the subsequent conversion factor positions 12 up to the simply hatched position 112. .. Positions 12 of all conversion factors following position 112 are shown to be unhatched in FIG. The gt2_flag 104 encoded during the path 60 ₂ is encoded in the portion 118 of the data stream immediately following the portion 114. Additional data between the path 60 ₂ after the position 116 is not encoded. The following two paths 60 _3, in 60 _4, it may be interpreted as forming one half of one path, the remainder is encoded into portions 120 of the data stream immediately following the portion 118. In particular, in the first sub-portion of portion 120, between the path 60 _3, the remainder is encoded in the position 12 of the transform coefficients to the position 112. Thus, these residues are the cross-hatched conversion factor position 12, the interval 110 for the conversion factor position 12 up to position 116, and simply the hatched conversion factor position 12, i.e. the position 112 following the position 116. Shows the absolute value of the quantized index at position 12 of a particular conversion factor in the remaining value domain, including intervals 108 and 110 for positions up to. After remaining sub-portion 122 of the position 12 of the transform coefficients to the position 112, while the path 60 _4, each position 12 of transform coefficients following the position 112, i.e., each position 12 of the transformation coefficients which are not hatched data stream There is one additional subpart 124 of the remainder encoded by. The remainder of the latter directly indicates the quantized index, i.e., the direct absolute value of the initial domain 90. Thus, the number of context-adaptive coding flags 92, 96, 98 and 104 is reduced and the number of bins encoded using bypass mode, i.e. fixed equal probability mode, i.e. the residual binary. Increase the bin of conversion.

That is, in FIG. 13, the above-mentioned abort criterion relates to whether or not the number of flags decoded in the first pass exceeds a predetermined threshold. In addition to sig_flag, type 96 and 98 flags are counted.

The variable length code for encoding / decoding the residual value for the position of the conversion factor currently being scanned may be selected from a set of predefined variable length codes such as Golomb rice code. The selected code is whether the currently scanned conversion factor position is located up to the predetermined conversion factor position 112, i.e., at the hatched position in FIG. 15, or the scan sequence 62. It may be different depending on whether or not it follows the position 112 of the predetermined conversion factor in FIG. 13, and in the case of FIG. 13, the selection depends on whether or not there is a position between the positions 112 and 116. May be. For example, different VLC code in pass 60 ₃ than the remainder of the coding / decoding path 60 ₄ or residual simply hatched coefficients of FIG. 15 in FIG. 13 in the 128 to encoding / decoding, is 15 It may even contain different codes as compared to the VLC code used in encoding / decoding the residue of the cross-hatched coefficients shown in 130. Selection can include parameterization of parameterizable VLC codes, such as the order of exponential Golomb codes or the selection of rice parameters as described below. Alternatively, the parameter indicating the selected variable length code is kept constant in the path 60 _3, it may be gradually changed in the quantization index at the transform coefficients preceding satisfy predetermined criteria. Alternatively, the binarization parameter may be selected in encoding the residue depending on the quantization index of the position of the conversion factor in the vicinity of the position of the conversion factor currently being scanned. This dependency is, for example, for all hatched positions in FIG. 15 at the position of the current conversion factor, where the residue is encoded, which is the position 112 of the conversion factor that precedes or is predetermined in the scan sequence 62. Used only if. Further details on this are outlined below.

Code word selected from the selected / parameterized code not, remainder also depends on the coefficient positions to be encoded / decoded: first and second paths 60 _{and second} flags 92 and 96, The absolute value of the quantized index minus the maximum value that can be represented by 98 and 104, that is, 4 plus 1, that is, 5 is represented, or if the quantized index belongs to a coefficient, the remainder of the quantized index of any coefficient. by binarization, VLC encoded is somewhere to the position 116, the absolute value of the quantization index obtained by subtracting the maximum value represented by the first pass 60 of _the flags 92,96,98 , That is, 2 plus 1, ie 3, is represented, or if the quantized index belongs to a coefficient, the VLC encoded by the binarization of the remainder of the quantized index of any coefficient is located after position 116. Somewhere up to 112, the absolute value of the quantized index is expressed directly, or in the case of the coefficient to which the quantized index belongs, it is encoded by the binarization of the remainder of the quantized index of any coefficient. The VLC is somewhere after position 112.

Some modifications of the embodiment of FIG. 13 may be applied. For example, Gt2_flag is not encoded / decoded in a separate path 60 _2, it may be included in the first pass 60 _1. Next, the number of gt2_flag encoded may also be included in the count of the context coding bins in the first pass 60 _1, the number of available context coding bin first if less than 4 The path ends. That is, in this case, a single threshold for the number of context-coded bins is used. Alternatively, gt2_flag is not transmitted at all, in which case the residue is encoded if gt1_flag is equal to 1.
Another variation of this embodiment includes one or more additional gtx_flags. Similar to gt2_flag, these flags are encoded only if the preceding gty_flag (y = x-1) is equal to 1, and the absolute value of the quantization index is greater than the minimum possible value specified by the preceding gtx_flag. Also indicates whether it is large or not. Next, the absolute value reconstruction is given by:

absLevel = sig_flag + par_flag + 2 * (gt1_flag + gt2_flag + gt3_flag + ... + reminder).

These flags can be encoded in the same path as gt2_flag, including when gt2_flag is included in the first path, or in one or more additional paths. In the latter case, additional thresholds can be applied to limit the number of gtx_flags.

The second embodiment described below differs from the first embodiment in one embodiment: the order of par_flag and gt1_flag is swapped (thus changing the meaning of these flags). If sig_flag is equal to 1, the first gt1_flag is transmitted, which specifies whether the absolute value of the conversion factor level is greater than 1. And if gt1_flag is equal to 1, par_flag specifies the residual parity (ie, absolute level-2). As in the first embodiment, the following applies:
● The state machine for dependent quantization is driven by the parity of the transformation factor level, that is, the binary function path (level) returns the parity of its argument;
● The probability model of sig_flag in the first pass is selected based on the corresponding values of the state variables (and optionally other parameters available to the decoder, see above).
First pass: The first pass for the scan position sends the following context-coded bins:
● sig_flag indicates whether the conversion factor is not equal to 0; if sig_flag can be estimated to be equal to 1 (eg, it is explicitly signaled by the first significant scan position (x and y coordinates) in the conversion block. In the case of), sig_flag is not transmitted.
● If sig_flag is equal to 1 (encoded or estimated value), the following is additionally sent for the current scan position:
○ gt1_flag specifies whether or not the absolute value is greater than 1.
○ If gt1_flag is equal to 1, par_flag specifies the absolute level of parity-2;
● When the predefined maximum number of context-coded bins is reached, the first pass ends. MAX_REG_BINS is the maximum number of bins that can be transmitted on the first pass, and regBins represents the number of positively coded bins that are still available. Then the following applies:
○ regBins is initially set equally to MAX_REG_BINS;
○ After encoding any bin (sig_flag, gt1_flag, par_flag), regBins is decremented by 1;
○ After sending bins for a scan position (sig_flag and, if applicable, gt1_flag and par_flag), the number of bins regBins still available is less than 3 (ie, sig_flag, par_flag for the next scan position). And gt1_flag cannot be sent), then the first scan pass ends.
Second pass: The second pass for the scan position sends the following context-coded bins:
● If gt1_flag at the scan position is equal to 1, gt2_flag is sent and specifies whether the residue (given by (absolute level-2-par_flag) / 2) is greater than 0.
● If a predefined maximum number of context-coded gt2_flags has been sent, the second pass ends. When the scan position where no data is transmitted in the first pass is reached (that is, no data is transmitted in the second pass for such a scan position), the second pass also ends.
Third pass: In the third pass with respect to the scan position, all sig_flag encoded in pass 1 with absolute level residuals (ie, data not already specified by the transmitted sig_flag, par_flag, gt1_flag and gt2_flag). Sent to the scan position of. The remainder of the non-binary syntax element is binarized using structured code (such as Golomb rice code) and the bins are encoded in the bypass mode of the arithmetic coding engine. The remainder is sent for the following scan positions:
● For all scan positions, gt2_flag equal to 1 is sent on the second pass:
For these scan positions, the residue of non-binary syntax elements sent specifies:
(Absolute value -4-par_flag) / 2
● For all scan positions, gt1_flag equal to 1 was sent in the first pass, but gt2_flag was not sent in the second pass:
For these scan positions, the residue of non-binary syntax elements sent specifies:
(Absolute value -2-par_flag) / 2
Fourth pass: In the fourth pass, the absolute levels for all scan positions where no data was transmitted in the first pass are encoded. The absolute level is first binarized using structured code, and the code used can rely on local activity measurements as well as the value of the current state variable. Bins are sent using the bypass mode of the arithmetic coding engine.
Fifth pass: Finally, in the fifth pass, the sign of all conversion factor levels not equal to 0 is transmitted. The code is transmitted in bypass mode of the arithmetic coding engine.
The pseudo code in FIG. 16 further illustrates the coding / decoding process at the conversion factor level within the subblock. The same comments as in the first embodiment apply. FIG. 17 shows a modified version of FIG. 14 that applies to FIG. FIG. 15 is also modified for FIG. 16 except for details such that the residue starts from the value domain related to the coefficients between positions 112 and 116, i.e. the maximum value using flags 92, 96 and 98. Is represented, which is 2 in the case of FIG. 13 and 1 in the case of FIG. As it is seen in addition to the case of FIG. 13, the encoding / decoding of the flag par_flag in the first pass 60 _1, the flag that quantization indices of transform coefficients that are corresponding scan is greater than one size It is performed exclusively for the position of the conversion coefficient indicated by gt1_flag and the position of the conversion coefficient thereafter. In the case of FIG. 13, this coding / decoding is necessarily performed in the non-zero case indicated by the corresponding sig_flag.

In a modification of this embodiment, gt2_flag is not encoded in another path and is included in the first path. The number of encoded gt2_flags is then included in the count of context-encoded bins in the first pass, ending the first pass if the number of available context-encoded bins is less than four. That is, in this case, a single threshold for the number of context-coded bins is used.

Alternatively, gt2_flag is not transmitted at all, in which case the residue is encoded when gt1_flag is equal to 1.

Another variation of this embodiment includes one or more additional gtx_flags. Similar to gt2_flag, these flags are encoded only if the preceding gty_flag (y = x-1) is equal to 1. Indicates whether the absolute value of the quantized index is greater than the minimum possible value specified by the preceding gtx_flag. Next, the absolute value reconstruction is given by:
absLevel = sig_flag + gt1_flag + par_flag + 2 * (gt2_flag + gt3_flag + ... + reminder)
These flags can be encoded in the same path as gt2_flag (including when gt2_flag is included in the first pass) or in one or more additional paths. In the latter case, additional thresholds may be applied to limit the number of gtx_flags.

The third embodiment differs from the first embodiment in one embodiment: the sig_flag in the first pass is encoded for all scan positions and only the presence of par_flag and gt1_flag has already been transmitted. Determined by the number of context coding bins. As in the first embodiment, the following applies:
● The state machine for dependent quantization is driven by the parity of the transformation factor level, that is, the binary function path (level) returns the parity of its argument;
● The probability model of sig_flag in the first pass is selected based on the corresponding values of the state variables (and optionally other parameters available to the decoder, see above).
First pass: The first pass for the scan position sends the following context-coded bins:
● sig_flag indicates whether the conversion factor is not equal to 0; if sig_flag can be estimated to be equal to 1 (eg, it is explicitly signaled by the first significant scan position (x and y coordinates) in the conversion block. In the case of), sig_flag is not transmitted.
● If sig_flag is equal to 1 (encoded or estimated value), the following is additionally sent for the current scan position:
○ par_flag specifies the value obtained by subtracting 1 from the absolute level parity;
○ gt1_flag specifies whether or not the residue (given by (absolute level-1-par_flag) / 2) is greater than 0.
● When the predefined maximum number of context-coded bins (which still contains the encoded sig_flag) is reached, the transmission of par_flag and gt1_flag is skipped. MAX_REG_BINS is the maximum number of bins that can be transmitted on the first pass, and regBins represents the number of positively coded bins that are still available. Then the following applies:
○ regBins is initially set equal to MAX_REG_BINS minus the sig_flag sent in the first pass (this number is the first scan index for the first pass, the last scan index of the subblock). And given by the information whether the subblock includes the first significance factor in the scan order);
○ After encoding any gt1_flag or par_flag, regBins is decremented by 1;
○ After sending bins for a scan position (sig_flag, and gt1_flag, par_flag if sig_flag is equal to 1), the number of bins still available regBins is less than 2 (ie, par_flag and for the next scan position). If gt1_flag cannot be transmitted), then only sig_flag is transmitted for all subsequent scan indexes in the first scan pass.
Second pass: The second pass for the scan position sends the following context-coded bins:
● If gt1_flag at the scan position is equal to 1, gt2_flag is sent and specifies whether the residue (given by absolute level -3-par_flag / 2) is greater than 0.
● If a predefined maximum number of context-coded gt2_flags has been sent, the second pass ends. If only sig_flag equal to 1 reaches the scan position transmitted in the first pass (ie, no data is transmitted in the second pass for such scan position), the second pass also ends. ..
Third pass: In the third pass with respect to the scan position, the absolute level residue (ie, the data not already specified by the transmitted sig_flag, par_flag, gt1_flag and gt2_flag) is coded in pass 1 with sig_flag and gt1_flag and par_flag. Sent for all converted scan positions. The remainder of the non-binary syntax element is binarized using structured code (such as Golomb rice code) and the bins are encoded in the bypass mode of the arithmetic coding engine. The remainder is sent for the following scan positions:
● For all scan positions, gt2_flag equal to 1 is sent on the second pass:
For these scan positions, the residue of non-binary syntax elements sent specifies:
(Absolute value-5-par_flag) / 2
● For all scan positions, gt1_flag equal to 1 was sent in the first pass, but gt2_flag was not sent in the second pass:
For these scan positions, the residue of non-binary syntax elements sent specifies:
(Absolute value-3-par_flag) / 2
Fourth pass: In the fourth pass, the absolute level minus 1 is encoded for all scan positions, and in the first pass only sig_flag equal to 1 is encoded (but gt1_flag is not transmitted). ). The residue (absolute level minus 1) is first binarized using structured code, and the code used may depend on local activity measurements as well as the value of the current state variable. can. Bins are sent using the bypass mode of the arithmetic coding engine.
Fifth pass: Finally, in the fifth pass, the sign of all conversion factor levels not equal to 0 is transmitted. The code is transmitted in bypass mode of the arithmetic coding engine.
The pseudo code in FIG. 18 further illustrates the coding process for the conversion factor level within the subblock. The same comments as in the first embodiment apply. 14 and 15 have also been modified for FIG. 18 and the fact that the coefficients 96 and 98 are no longer encoded according to the scan sequence 62, while the sig_flag indicates where position 112 is available throughout the block. Except for, the residue for position 112 downstream of the conversion position, i.e. unhatched, does not represent the quantized index of the corresponding coefficient, but rather the residue indicates that its sig_flag is non-zero and subtracts 1. It is encoded for the coefficient after position 112, which indicates only the absolute level of the quantized index.

Note that after the first sig_flag equal to 1 is encoded, the state variable is unknown and gt1_flag / par_flag does not follow. Therefore, for subsequent sig_flags, the probabilistic model used must be derived independently of the state variables (which still depend on the state variables for the preceding sig_flag).

The following modifications of the third embodiment are possible.
1. 1. The state machine is driven by sig_flag (ie, information on whether the conversion factor level is equal to or not equal to zero). The binary function path specifies whether the level is not equal to zero. In this case, the parity flag does not need to be transmitted, and only the following data is added to sig_flag and transmitted.
● First pass: gt1_flag (sig_flag transmission is equal to 1; specifies whether the absolute level is greater than 0;
● Second pass: gt2_flag (sending gt1_flag is equal to 1; specifies whether the absolute level is greater than 2.
This has the advantage that the state variable is known for all sig_flags and therefore the probabilistic model used to encode the sig_flag can be selected based on the state variable. In addition, gt1_flag is removed from the first path and can be encoded in a separate path as follows:
● First path: transmission of sig_flag ● Second path: transmission of gt1_flag (up to the maximum number of gt1_flag)
● Third pass: transmission of gt2_flag (up to the maximum number of gt2_flag)
● Fourth pass: (a) gt2_flag equal to 1 was sent, (b) gt1_flag equal to 1 was sent, but gt2_flag was not sent Residual scan index ● Fifth pass: sig_flag is 1 Absolute level equal to, but minus 1 for scan positions where gt1_flag was not transmitted ● 6th pass: Code for all conversion factor levels not equal to 0

2. 2. The state machine switches from a parity drive state machine to an important drive state machine. It means the following:
● For all scan indexes where regBins (specified in the pseudocode above) is greater than or equal to 2, state variables are updated using parity (ie, the binary function path is conversion factor level parity. );
● After regBins is less than 2, the state variables are updated with significant information (ie, the binary function path (level) specifies whether the level is not equal to 0).
This has the advantage that the state variables are known for all sig_flags, so the probabilistic model used to encode the sig_flag may be selected based on the state variables. In contrast to Transform 1 (the state machine is always driven by sig_flag), higher compression densities in N-dimensional space and the next higher coding efficiency are achieved.

That is, the update of the state transitioning state is such that the position of the current conversion factor given by k in FIG. 10 precedes in the scan order 62, or in the predetermined conversion factor position 112, ie FIG. or those hatched, or exceeds the latter range, i.e. in the scan 60 _1, to the extent that depends on whether a position that is not hatched shown in Figure 15, just as the parity drive The state transitioned at 76 described may have been changed so far. A second flag type of the current conversion factor position if the current conversion factor position does not exceed or is equal to or earlier than the conversion factor position 112, which is predetermined according to the scan order 62. Flag 96, i.e., the parity described earlier, depends on subsequent updates, but the position of the current conversion factor follows, i.e., exceeds the position of the predetermined conversion factor in the scan order, ie according to the scan order 62, and is converted. The update depends on the first flag of the position of the coefficient, i.e. it depends on the zero value of the current coefficient. This may then be utilized in context-adaptive entropy decoding of a predetermined first flag type flag, i.e., according to the present embodiment, relating to the representation of the quantized index of each coefficient. The sig_flag to exceed the coefficient position 112 other than the gt1 flag at which the parity flag and its coding are stopped at 112: therefore, for all conversion coefficients that occur first, include, and exceed the position 112 of the predetermined conversion coefficient. For a position, the decoder and encoder determine the context of such a sig_flag for the currently scanned conversion factor, depending on the expected state for the position of the conversion factor for which the state transition is currently being scanned. Is possible.

Alternatively, state updates are performed in any way that is simply parity driven, and the context for sig_flag up to position 112 is performed independently of position 112 and based on the state of dependent quantization. ..

Similar to the first embodiment, the following modifications are possible.
● The first pass includes gt2_flag;
● gt2_flag is not coded at all;
● An additional gtx_flag is encoded.

That is, in the third embodiment, there is a predetermined first flag type flag 92, that is, sig_flag, and a predetermined second flag type flag 96, that is, par_flag. As in the case, the flag limiting the absolute value domain of the quantization index for the position of the first conversion coefficient is the quantum for the position of the second conversion coefficient following the position of the first conversion coefficient in scan sequence 62. They are encoded / decoded so that they are encoded / decoded before the flags that limit the absolute value domain of the quantized index.
That is, any sig_flag [k] and par_flag [k] are encoded / decoded before the sig_flag [k + 1] and par_flag [k + 1]. However, except in the case of FIG. 13, the coding / decoding of the predetermined second flag type flag, that is, par_flag, is the position 112 of the predetermined conversion factor shown by “startldxByass-1” in FIG. until runs, in the first pass 60 _1, the abort criterion is first met in accordance with the scanning order 62 - for example, the number of encoded flag in the first pass 60 _1, exceeds a certain threshold - is predetermined The coding / decoding of the flag of the first flag type, i.e. sig_flag, is performed in scan sequence 62 beyond the position 112 of the predetermined conversion factor, i.e., eg, for all conversion factors, or in all. Instead, the first non-zero quantization index for position 64 is performed without investigating any abort criteria.

The fourth embodiment differs from the third embodiment in one embodiment: the order of par_flag and gt1_flag is swapped (and the meaning of these flags is changed accordingly). If sig_flag is equal to 1, the first gt1_flag is transmitted and specifies whether the absolute value of the conversion factor level is greater than 1. Then, if gt1_flag is equal to 1, par_flag specifies the residual parity (ie, absolute level-2). As in the first embodiment, the following applies:
● The state machine for dependent quantization is driven by the parity of the transformation factor level, that is, the binary function path (level) returns the parity of its argument;
● The stochastic model of sig_flag in the first pass is selected based on the values of state variables (and optionally other parameters available to the decoder, see above).
First pass: The first pass for the scan position sends the following context-coded bins:
● sig_flag indicates whether the conversion factor is not equal to 0; if sig_flag can be estimated to be equal to 1 (eg, it is explicitly signaled by the first significant scan position (x and y coordinates) in the conversion block. In the case of), sig_flag is not transmitted.
● If sig_flag is equal to 1 (encoded or estimated value), then the following is additionally sent for the current scan position:
○ gt1_flag specifies whether or not the absolute level is greater than 1.
If gt1_flag is equal to 1, par_flag specifies the absolute level parity minus 2.
● When the predefined maximum number of context-coded bins (which still contains the encoded sig_flag) is reached, the transmission of par_flag and gt1_flag is skipped. MAX_REG_BINS is the maximum number of bins that can be transmitted on the first pass, and regBins represents the number of positively coded bins that are still available. Then the following applies:
○ regBins is initially set equal to MAX_REG_BINS minus the sig_flag sent in the first pass (this number is the first scan index for the first pass, the last scan index of the subblock). And given by the information whether the subblock includes the first significance factor in the scan order);
○ After encoding any gt1_flag or par_flag, regBins is decremented by 1;
○ After sending bins for a scan position (sig_flag, and gt1_flag, par_flag if sig_flag is equal to 1), the number of bins still available regBins is less than 2 (ie, par_flag and for the next scan position). If gt1_flag cannot be transmitted), then only sig_flag is transmitted for all subsequent scan indexes in the first scan pass.
Second pass: The second pass for the scan position sends the following context-coded bins:
● If gt1_flag at the scan position is equal to 1, gt2_flag is sent and specifies whether the residue (given by absolute level -2-par_flag / 2)) is greater than 0.
● If a predefined maximum number of context-coded gt2_flags has been sent, the second pass ends. If only skip_flag equal to 1 reaches the scan position transmitted in the first pass (ie, no data is transmitted in the second path for such scan position), the second pass also ends. ..
Third pass: In the third pass with respect to the scan position, the absolute level residue (ie, the data not already specified by the transmitted sig_flag, par_flag, gt1_flag and gt2_flag) is coded in pass 1 with sig_flag and gt1_flag and par_flag. Sent for all converted scan positions. The remainder of the non-binary syntax element is binarized using structured code (such as Golomb rice code) and the bins are encoded in the bypass mode of the arithmetic coding engine. The remainder is sent for the following scan positions:
● For all scan positions, gt2_flag equal to 1 is sent on the second pass:
For these scan positions, the residue of non-binary syntax elements sent specifies:
(Absolute value -4-par_flag) / 2
● For all scan positions, gt1_flag equal to 1 was sent in the first pass, but gt2_flag was not sent in the second pass:
For these scan positions, the residue of non-binary syntax elements sent specifies:
(Absolute value -2-par_flag) / 2
Fourth pass: In the fourth pass, the absolute level minus 1 is encoded for all scan positions, and in the first pass only sig_flag equal to 1 is encoded (but gt1_flag is not transmitted). ). The residue (absolute level minus 1) is first binarized using structured code, and the code used may depend on local activity measurements as well as the value of the current state variable. can. Bins are sent using the bypass mode of the arithmetic coding engine.
Fifth pass: Finally, in the fifth pass, the sign of all conversion factor levels not equal to 0 is transmitted. The code is transmitted in bypass mode of the arithmetic coding engine.
The pseudo code in FIG. 19 further illustrates the coding process for the conversion factor level within the subblock. The same comments as in the first and third embodiments apply. 17 and 15 are also modified for FIG. 19, however, in FIG. 15, the residue is the remainder with respect to the coefficients between positions 112 and 116, i.e., the maximum that can be represented using flags 92, 96 and 98. The value is changed to the start of the value domain of 2, in the case of FIG. 13, and 1, in the case of FIG.

The fourth embodiment can be modified in the same manner as the third embodiment. This includes the following aspects (similar to Embodiment 2).
● The first pass includes gt2_flag;
● gt2_flag is not coded at all;
● An additional gtx_flag is encoded.

That is, the variable length code for encoding / decoding the residual value for the position of the conversion factor currently being scanned is a predefined variable length code, such as a set of Golomb rice codes that differ from each other by RP. Can be selected from the set. The choice depends on whether the currently scanned conversion factor position where the residue is encoded / decoded is located up to the predetermined conversion factor position 112 or downstream of it in the scan sequence 62. May be. That is, different RPs are selected in the former and the latter cases. According to methods 1 and 2 described above, the RP parameters indicating the selected variable length code may generally _{be kept constant between the paths 60 3,4} , but as in method 1, certain limitations. Near the quantized index of the preceding decoded / coded conversion factor that meets a predetermined criterion that exceeds, or the position of the currently scanned conversion factor that meets some criteria that exceed a certain limit. Can be gradually changed to the quantized index at the conversion position. For example, only if the position of the current conversion factor with the residue encoded is placed up to the predetermined conversion factor position 112, i.e. for all hatched positions in FIG. You can use this dependency or incremental change. In addition to the quantized index of the coefficients in the neighborhood, the dependent quantized state may be used to select the binarized code parameter.

The following embodiments can be combined with the above-described embodiments, but may be optionally implemented in the above-described embodiments in order to increase the coding efficiency. This aspect relates to explicit signaling of blocks / subblocks that do not contain any of the conversion factor levels with absolute values greater than 1.

Dedicated flags are introduced on a conversion block or subblock basis to reduce the number of bins for encoding conversion factor levels, and whether the absolute level within the block or subblock is greater than 1 in any case. Signaling:
● If the subblock with coded_subblock_flag is equal to 1 (encoded or estimated), a second flag is transmitted for the subblock. This flag (gt1_subblock_flag) specifies whether the subblock contains any conversion factor level with an absolute level greater than 1.
● If gt1_subblock_flag is equal to 0, only the significant information (sig_flag) and the sign bit of the conversion factor level not equal to 0 are transmitted.
● If gt1_subblock_flag is equal to 1, the coding of the conversion factor level proceeds as described in embodiments 1-4. Further states in which it is possible to estimate that when the last scan index in a subblock is reached and all preceding absolute levels in the subblock are equal to 1, then the last absolute level is greater than 1. May include. -Therefore, the corresponding gt1_flag can be estimated to be equal to 1. Also for embodiments 1 and 3, the parity flag par_flag can be estimated to be equal to 0 in this case.
A flag specifying that all levels have an absolute value equal to 1 can also be sent to the entire conversion block based on the subblock instead. It is also possible to send this flag only to the selected subblock (eg, the subblock containing the first significance factor).

That is, here, the conversion coefficient block 10 is encoded / decoded by the following method. Whether or not each subblock 14 contains a conversion factor 12 whose absolute value of the quantization index is greater than a predetermined non-zero threshold for each of at least one set of subblocks 14 to which the conversion factor block 10 is divided. A subblock serious flag indicating such as, that is, gt1_subblock_flag is transmitted. The conversion factor of the conversion factor block in each subblock 14 that the subblock severity flag indicates that there is at least one conversion factor whose absolute value of the quantization index is greater than the predetermined non-zero threshold, is the respective conversion. Coefficient value One or more flags 92, 96, 98, 194 that recursively divide the domain into two parts and indicate in which of the two parts the quantized index of each conversion factor is located. Or the sequence of other flags is encoded / decoded as described above by sequentially encoding / decoding each of the conversion coefficients in each subblock so that the value domain defines the signed value. When interpreted, it involves stopping the decoding of the sequence as soon as the value domain contains only one value or an absolutely equal value. If the value domain still contains one or more values that differ in the absolute sense, the residual value indicating the absolute value of the quantized index of each conversion factor in the value domain is encoded / decoded. However,
Within each subblock where the subblock severity flag indicates that there is no conversion factor whose absolute value of the quantization index is greater than the predetermined non-zero threshold.
Subsequent decoding of a sequence of one or more flags for each of the conversion factors within each subblock
It is stopped as soon as the value domain contains only one value that does not exceed the nonzero threshold, just one value or just an absolutely equal value. One such value previously encoded for each coefficient, satisfying the requirement indicated by the subblock severity flag by not exceeding the index of all coefficients in each subblock above a predetermined non-zero threshold. The first stop criterion arises from the fact that the remaining value domain or the remaining value interval simply contains, as determined by the / decrypted flag, so this one value in this value domain is the quantized index. Is.

Thus, among other things, the following embodiments have been described above.

A2.4 The device of any of embodiments B5 or A1 configured to perform the transition of the state transition between four different states.

A3. Depending on the binary function applied to the quantized index at the position of the current conversion factor in updating the state of the state transition, between the first and second successor states. Embodiment B5 or A1-A2, wherein the first successor state and the second successor state depend on the state at the position of the current conversion factor, configured to perform the update by determination. The device described in any.

A4. The device of any of embodiments B5 or A1-A3, wherein the binary function produces said parity or zero.

A5. Embodiments B5 or A1- configured to parameterize the plurality of quantization level sets with a predetermined quantization step size and derive information about the predetermined quantization step size from the data stream. The device according to any one of A4.

A6. The embodiment B5 or A1-A5, wherein each of the plurality of quantization level sets comprises a multiple of a predetermined quantization step size that is constant for the plurality of quantization level sets. Device.

A7. Of the plurality of quantization level sets, the number of the quantization level sets is 2, and the plurality of quantization level sets are a first quantum containing zero and an even multiple of a predetermined quantization step size. The apparatus according to any of embodiments B5 or A1-A6, comprising a quantization level set and a second quantization level set comprising zero and an odd multiple of the predetermined quantization step size.

A8. In the first pass of the sequence of the paths, the decoder has a flag in the scan order that limits the value domain of the absolute value of the quantization index for the position of the first conversion factor. To be decoded before the flag limiting the value domain of the absolute value of the quantization index for the position of the second conversion factor following the position of the conversion factor of (ie, any sig_flag [k + 1] and par_flag [i.e. Any sig_flag [k] and par_flag [k] before k + 1], a predetermined first flag type flag (eg, sig_flag) and a predetermined second flag type flag (eg, par_flag). ) From the data stream (eg, embodiments 3 and 4), wherein the decoding of the predetermined second flag type flag is predetermined abort in the first pass. Predetermined conversion factor positions (eg, embodiment 3: startIdxBypass-1) where the criteria are met for the first time in said scan order (eg, the number of encoded flags in the first pass exceeds a certain threshold). ), And the decoding of the predetermined first flag type flag is performed in the scan order for the position of the predetermined conversion factor (for all of the encoded sets, or any abort). For the first non-zero quantization index where the reference has not been measured), the flag of the predetermined first flag type is the quantization index of the currently scanned conversion factor. The device according to any one of embodiments A1-A7, which indicates whether or not it is zero (eg, sig_flag).

A9. The apparatus of embodiment A8, wherein the flag of the predetermined second flag type indicates the parity of the quantized index for the currently scanned conversion factor.

A10. In the first pass, the position of the conversion factor and subsequent conversion indicating that the quantization index of the conversion factor in which the flag of the first predetermined flag type is currently scanned is non-zero. The apparatus according to any of the preceding embodiments A8-A9, configured to exclusively decode the flag of the second predetermined flag type with respect to the position of the coefficients.

A11. The apparatus according to embodiment A8, wherein the predetermined abort criterion is related to the number of flags decoded in the first pass exceeding a predetermined threshold.

A12. A third, indicating whether or not in the first pass, the quantization index for the position of the currently scanned conversion factor is assumed to be the smallest value within the value domain with respect to the absolute value. The apparatus according to any of the preceding embodiments A8-A11, which is configured to also decode a flag of a predetermined flag type.

A13. In the first pass, the position of the conversion factor indicated by the flag of the first predetermined flag type that the quantization index for the currently scanned conversion factor is non-zero and thereafter. The apparatus according to embodiment A12, which is configured to exclusively decode the flag of the third predetermined flag type with respect to the position of the conversion factor.

A14. In the first pass, the position of the conversion factor and the position of the conversion factor indicated by the flag of the first predetermined flag type that the quantization index for the position of the currently scanned conversion factor is non-zero. Embodiment A13 (eg,) configured to decode the flag of the third predetermined flag type after the flag of the second predetermined flag type with respect to the position of the subsequent conversion factor. , The apparatus according to the third embodiment).

A15. In the first pass, the position of the conversion factor and the position of the conversion factor indicated by the flag of the first predetermined flag type that the quantization index for the position of the currently scanned conversion factor is non-zero. With respect to the position of the conversion coefficient thereafter, the position of the conversion coefficient indicating that the flag of the third predetermined flag type has a magnitude larger than 1 is exclusively for the position of the second predetermined flag type. The device according to embodiment A13 (eg, embodiment 4) configured to decode the flag.

A16. In the second pass following the first pass, the first that the quantization index for the position of the currently scanned conversion factor is the smallest value in the value domain with respect to the absolute value. Any of the preceding embodiments A8-A15 configured to also decode a flag of a fourth predetermined flag type indicating whether or not it is expected to be restricted by the flag being decoded in the path of. The device described in.

A17. The apparatus according to embodiment A16, which is configured to decode the residual value in one or more additional paths following the second path.

A18. The apparatus according to embodiment A8-A17, which is configured to decode the residual value in one or more paths following the first path.

A19. The apparatus according to embodiment A8-A18, which is configured to decode the sign of the non-zero conversion factor in the last pass.

A20. The decoder 1) in the state transition-the position of the current conversion factor precedes or equals the position of the predetermined conversion factor in the scan order. In some cases, for the position of each of the conversion factors-depending on the flag of the second flag type of the position of the current conversion factor (eg, embodiment 3: par_flag)-the present. If the position of the conversion factor of is followed by the position of the predetermined conversion factor in the scan order, then-with respect to the position of the respective conversion factor, the first flag of the position of the current conversion factor. Depending on the type of flag (eg, embodiment 3: path (level) yields zero), it is configured to perform the update of the state of the state transition (eg, embodiment 3, th. Modification example of 2 "2. The state machine switches from the parity drive state machine to the important drive state machine.")) 2) In the context-adaptive entropy decoding, the state transition is the conversion coefficient of the current scanned conversion coefficient. The currently scanned conversion factor for all positions of the conversion factor preceding, including, and following the position of the predetermined conversion factor, depending on the assumed state of the position. A device according to any of the preceding embodiments A8-A19, configured to determine a context for decoding a flag of said predetermined first flag type with respect to.

A21. The apparatus assumes in the context-adaptive entropy decoding the position of the conversion factor for which the state transition is currently scanned for the position of the conversion factor preceding and including the position of the predetermined conversion factor. Depends on said state and the position of the conversion factor following the position of the predetermined conversion factor is independent of the state where the state transition assumes for the position of the currently scanned conversion factor. And configured to determine the context for decoding the flag of the predetermined first flag type with respect to the position of the currently scanned conversion factor (eg, Embodiment 3), precedent. The apparatus according to any one of embodiments A8-A19.

A22. The decoder 1) in the context-adaptive entropy decoding, the predetermined conversion factor position (112) depends on the state that the state transition assumes for the position of the conversion factor currently being scanned. Decrypts the predetermined first flag type flag (92) for the currently scanned conversion factor position for all said conversion factor positions preceding, including and subsequent to. 2) In the state transition, the flag of the first flag type at the position of the current conversion factor (eg, embodiment 3: path (level) is zero. With respect to the position of the conversion factor following the position of each of the conversion factors in the scan order, the said state of the state transition assumed for the position of the current conversion factor. The apparatus according to any of the preceding embodiments A8-A19 configured to perform the update (eg, Embodiment 3: First Modification).

B2. Whether the position of the currently scanned conversion factor precedes the position of the predetermined conversion factor in the scanning order, or is the position of the predetermined conversion factor, or the position of the predetermined conversion factor. The variable length code is configured to be parameterized in order to differently decode the residual value for the position of the currently scanned conversion factor, depending on whether or not it follows the position of. The device according to embodiment B1.

B3. The currently scanned conversion factor is currently scanned if the position of the currently scanned conversion factor precedes (in the scanning order) the position of the predetermined conversion factor or is equal to the position of the predetermined conversion factor. To decode the residual value for the position of the conversion factor, by gradually changing it to the quantization index of the position of the preceding conversion factor that meets a predetermined criterion, and / or the current scan. The apparatus according to embodiment B1 or B2, wherein the variable length code is configured to be parameterized depending on the quantization index of the conversion coefficient position in the vicinity of the conversion coefficient position.

B4. If the position of the currently scanned conversion factor follows the position of the predetermined conversion factor in the scanning order, to decode the residual value for the position of the currently scanned conversion factor. The state transition depends on the quantization index of the position of the conversion factor in the vicinity of the position of the currently scanned conversion factor, and the state transition depends on the state assumed for the position of the currently scanned conversion factor. The device according to embodiment B1 or B2 or B3, which is configured to parameterize the variable length code.

B5. The decoder selects one set of reconstruction levels from a plurality of reconstruction level sets a) for the position of the current conversion factor, based uniquely on the state that the state transition assumes for the position of the current conversion factor. Then, the quantization index dequantizes the quantization index to the reconstruction level pointed to in the set of reconstruction levels, and b) depends on the quantization index for the position of the current conversion factor. And because of the position of the conversion factor following the position of the current conversion factor in the scan order (note that the term currently indicates the intended purpose or effect of the update). Note that the position of the current conversion factor, said, which is currently being scanned during dependent quantization; what is "currently scanned" is currently being decoded during the path. By updating the state of the assumed state transition for (used to represent what is), the position of the conversion factor using the state transition (see, eg, trellis diagram). Embodiment B1 configured to continuously dequantize (ie, use dependent quantization) the quantization index at the position of the conversion factor of the encoded set of. Or the device according to any one of B4.

3. 3. Each of the set of one or more flag types is configured to perform the decoding in one of the sequences of the paths so as to decode the flags of the respective flag types. The device according to any one of embodiments A1-A22 or B1-B5.

4. The device according to any of the preceding embodiments (eg, embodiments 1 to 4), wherein the variable length code is a Golomb rice code.

5. The apparatus gradually changes it to the quantization index at the position of the preceding conversion factor that meets a predetermined criterion in order to decode the residual value for the position of the currently scanned conversion factor. And / or depending on the quantization index of the conversion factor position in the vicinity of the currently scanned conversion factor position, the variable length code is configured to be parameterized (eg,). , Methods 1 and 2) in embodiments 1 to 4,4.5.4, the apparatus according to any of the preceding embodiments.

6. Between said position of the first non-zero quantization index in the scan order and the position of the predefined conversion factor, the coded set of positions of the conversion factor extending according to the scan order is determined and said data. The device according to any of the preceding embodiments configured to identify said position of the first non-zero quantized index based on the stream (eg, embodiments 1 to 4).

7. The device according to any of the preceding embodiments configured to decode the sign bit from the data stream using an equal probability bypass mode for each nonzero quantization index.

10. Use context-adaptive entropy decoding by selecting the flag of the first flag type for a predetermined conversion factor position depending on the coefficient position of the predetermined conversion factor. The device according to any of the preceding embodiments, which is configured to decode.

11. a) Decoding before the flag of the predetermined flag type of the predetermined conversion factor position for a set of nearby conversion factor positions in the local template around the predetermined conversion factor position. The first pre-determined for the position of the pre-determined conversion factor by determining the local activity based on the set of flags set and b) selecting the context depending on the local activity. The device according to any of the preceding embodiments configured to decode said flag of a determined flag type using context-adaptive entropy decoding.

12. The set of flags includes the flag of the predetermined first flag type decoded for the set of positions of conversion coefficients in the vicinity and the flag of the predetermined second flag type. , The flag of the predetermined third flag type (at least; may be more, such as 4), and the device adds to each of the positions of the conversion factors in the vicinity. The activity is calculated based on the sum of the above, and the addition is decoded (at least) for the position of the conversion factor in the vicinity of the flag of the predetermined first flag type. For the quantization index for the position of the conversion factor in the neighborhood determined based on the flag of the predetermined second flag type and the flag of the predetermined third flag type. The apparatus according to the eleventh embodiment, which indicates the minimum assumed absolute value or the minimum assumed absolute quantization level.

13. The decoder provides one reconstruction level set from a plurality of reconstruction level sets, 1) a) for each conversion coefficient position, based on the state that the state transition assumes for each conversion coefficient position. Select to inversely quantize the quantization index to the reconstruction level indicated by the reconstruction level set, and b) depend on the quantization index at the position of the current conversion factor. And because of the position of the conversion factor following the current conversion factor in the scan order (note that the term currently indicates the intended purpose or effect of the update). The position of the current conversion factor (note that this is what is currently being scanned during dependent quantization; what is "currently scanned" is what is currently being decoded during the path. By updating the state of the assumed state transition for (used to represent), the state transition according to the scan order (see, eg, trellis diagram) is continuously used. It is configured to be dequantized (ie, the use of dependent quantization), 2) said the flag of the first flag type with respect to the position of the predetermined conversion factor, and said the state transition is the predetermined transformation. Context-adaptive entropy decoding is performed by selecting the context depending on the assumed state for the position of the coefficients and / or the set of reconstruction levels selected for the position of the predetermined conversion factor. The device of any of the preceding embodiments configured to be used and decoded (eg, embodiments 1-4).

20. Context-adaptive entropy decoding is used by selecting the context of the flag of the second flag type for the position of the predetermined conversion factor depending on the coefficient position of the predetermined conversion factor. The device according to any of the preceding embodiments, which is configured to decode.

21.1) For a set of neighborhood conversion coefficient positions in a local template around a predetermined conversion coefficient position, the second predetermined flag type of the predetermined conversion coefficient position. Based on the set of flags decrypted before the flags, the quantization index in the local template around the position of the local activity and / or the predetermined conversion factor is a non-zero conversion factor. For the position of the predetermined conversion factor by determining the number and / or selecting the context depending on the number of the local activity and / or the non-zero quantization index. The apparatus according to any of the preceding embodiments configured to decode the flag of the second predetermined flag type of the above using context adaptive entropy decoding.

22. 21. The apparatus of embodiment 21, configured to select the context depending on the difference between the local activity and the number of non-zero quantized indexes.

23. The set of flags includes the flag of the predetermined first flag type decoded for the set of positions of conversion coefficients in the vicinity and the flag of the predetermined second flag type. , The flag of the predetermined third flag type (eg, encoded in the first scan path, also for embodiment 12), the apparatus of which the apparatus is located in the vicinity of the conversion factor. The activity is calculated based on the sum of the additions for each of the above, and the addition is decoded for the position of the conversion factor in the vicinity of the predetermined first flag type. Based on the flag, the flag of the predetermined second flag type, and the flag of the predetermined third flag type (more flags are transmitted in the first pass). Note that more flags can be used than the above flags if 20 or 21. The apparatus of embodiment 20 or 21, indicating a quantization index.

33. Context-adaptive entropy decoding is used by selecting the context of the flag of the third flag type for the position of the predetermined conversion factor depending on the coefficient position of the predetermined conversion factor. The device according to any of the preceding embodiments, which is configured to decode.

31.1) The second predetermined flag type of said predetermined conversion factor for a set of nearby conversion factor positions in a local template around the predetermined conversion factor position. Based on the set of flags decoded before the flags, the quantization index of the non-zero conversion factor in the local template around the position of the local activity and / or the predetermined conversion factor. Said for a predetermined conversion factor position by determining the number and / or selecting the context depending on the number of the local activity and / or the non-zero quantization index. A device according to any of the preceding embodiments configured to decode said flag of a third predetermined flag type using context adaptive entropy decoding.

32. 31. The apparatus of embodiment 31, wherein the context is configured to depend on the difference between the local activity and the number of non-zero quantized indexes.

33. The set of flags includes the flag of the predetermined first flag type decoded for the set of positions of conversion coefficients in the vicinity and the flag of the predetermined second flag type. Including said flag of the predetermined third flag type (see notes of embodiments 12 and 23), the device is added to the sum of the additions for each of the positions of the conversion factors in the vicinity. The activity is configured to be calculated based on the flag of the predetermined first flag type decoded for the position of the conversion factor in the neighborhood and the predetermined first flag. Regarding the position of the conversion factor in the vicinity determined based on the flag of the flag type 2 and the flag of the predetermined third flag type (see notes in embodiments 12 and 23). The apparatus according to embodiment 30 or 31, which indicates the minimum assumed absolute value or the minimum assumed absolute quantization index for the quantization index.

C1. A decoder for decoding a conversion factor block: 1) For each of at least one set of subblocks in which the conversion factor block is divided, each of the subblocks has an absolute value of the quantization index. Decoding the subblock critical flag indicating whether it contains a conversion factor greater than the predetermined non-zero threshold, and 2) the absolute value of the quantization index is greater than the predetermined non-zero threshold. Within each subblock indicated by the subblock severity flag that there is at least one large conversion factor, a) for each of the conversion factors in each of the subblocks, the value domain of the respective conversion factor. It is inductively divided into two parts, and continuously decodes a sequence of one or more flags indicating which of the two parts the quantization index of each conversion coefficient is located in, and continuously decodes the sequence. Stop decoding the sequence as soon as the value domain contains only one value or values that are absolutely equal, and the value domain still contains one or more values that differ in the absolute sense. When included, the absolute value of the quantization index in the value domain is determined in advance by continuously decoding the residual value indicating the absolute value of the quantization index of each of the conversion coefficients. Within each subblock indicated by the subblock critical flag that no conversion factor greater than the non-zero threshold exists, b) for each of the conversion factors within each of the subblocks, of the one or more flags. Decoding the sequence as soon as the value domain contains only one value that does not exceed the non-zero threshold, just one value or simply an absolutely equal value, while continuously decoding the sequence. A decoder configured to decode the conversion factor of the conversion factor block by stopping.

C2. The apparatus according to embodiment C1, wherein the first flag of the sequence flag is a significant flag indicating whether or not the conversion coefficient from which the first flag is decoded is zero.

C3. The predetermined non-zero threshold is 1 and the device is within each subblock indicated by the subblock critical flag that there is no conversion factor for which the absolute value of the quantization index is greater than 1. The apparatus according to embodiment C2, wherein the first flag is continuously decoded for each of the conversion coefficients in each of the subblocks.

C4.1) For each of at least one other set of the sub-blocks in which the conversion factor blocks are divided, another sub-indicating whether each of the sub-blocks contains a conversion factor that is not equal to zero. Decoding the block critical flag, 2) said set of subblocks that make up the subblock indicated by said another subblock critical flag that the subblock critical flag is decoded and contains at least one conversion factor that is not equal to zero. 3) Within each subblock indicated by the other subblock critical flag that the non-zero conversion factor does not exist, the conversion factors of the conversion factor block are all estimated to be zero. The device according to any of the preceding embodiments C1-C3.

The above description presents the concepts of conversion factor level (quantization index) quantization and entropy coding for block-based hybrid video coding. The techniques outlined above may be applied to Rossy coding of blocks of residual samples. The residual sample can represent the difference between the original block of the sample and the sample of the prediction signal (the prediction signal can be an intra-picture prediction or an inter-picture prediction, or a combination of inter-picture and intra-picture prediction, or any other means. Can be obtained by; in special cases, the prediction signal may be set equal to zero).

The sample residual block may be transformed using signal conversion. Typically, linear and separable transformations are used (linear is linear, but can incorporate additional rounding of transformation coefficients). Often, the integer approximation of DCT-II or the integer approximation of other transformations of the DCT / DST family is used. Different transformations can be used horizontally or vertically. Transformations are not limited to linear and separable transformations. Any other transformation (linear and non-separable, or non-linear) may be used. The result of the signal conversion is a block of conversion coefficients that represents the original block of the residual sample in different signal spaces. In special cases, the transformation can be equal to the discriminative transformation (ie, the block of transformation coefficients can be equal to the block of the residual sample). Blocks of conversion coefficients are coded using Rossy coding. On the decoder side, the blocks of the reconstructed conversion coefficients are inversely transformed to obtain the reconstructed blocks of the residual sample. Finally, by adding the prediction signals, a reconstructed block of the image sample is obtained.

In particular, the following embodiments, which are suitable for Rossy coding of blocks of conversion factors, are used in the embodiments described above:
● Dependent scalar quantization of conversion factor:
On the encoder side, the blocks of conversion factors are mapped to blocks at the conversion factor level (ie, the quantization index), which represent the conversion factors with reduced fidelity. On the decoder side, the quantization index is mapped to the reconstructed conversion factor (which is different from the original conversion factor due to quantization). In contrast to traditional scalar quantization, the conversion coefficients are not quantized independently. Instead, the acceptable set of reconstruction levels for a particular conversion factor depends on the quantization index selected for the other conversion factors.
● Entropy coding of conversion coefficient level (quantization index):
The conversion factor level, which represents the reconstructed conversion factor (for dependent scalar quantization), is entropy-coded using binary arithmetic coding. In that context, the properties of dependent quantization are utilized to improve the efficiency of entropy coding.

Different embodiments and embodiments have been described above. The description relates to various aspects such as flag / residual representation, distribution of flags and residuals to paths, context derivation, and restrictions on flags adaptively encoded in context. These aspects, features, functions, and details described in different parts can optionally be introduced individually or together into the embodiments described herein.
The embodiments described herein can also be used individually and supplemented by any of the features, functions, and details in other chapters.
It should also be noted that the individual embodiments described herein may be used individually or in combination. Therefore, details can be added to each of the individual embodiments without adding details to the other one of the embodiments.
In particular, embodiments are also described in the claims. The embodiments described in the claims may optionally be supplemented individually and in combination by any of the features, functions and details as described herein.
The present disclosure, expressly or implicitly, a video encoder (a device for providing a coded representation of an input video signal) and a video decoder (a device for providing a coded representation of a video signal) and a video decoder (a device for decoding a video signal based on the coded representation of the video signal). The features that can be used in the device for providing the expression) are described. Accordingly, any of the features described herein can be used in the context of video encoders and video decoders.
In addition, the features and functions disclosed herein in relation to the method can also be used in devices (configured to perform such functions). In addition, the features and functions disclosed herein with respect to the device can also be used in the corresponding methods. In other words, the methods disclosed herein can be supplemented by any of the features and functions described with respect to the device.
Also, any of the features and features described herein can be implemented in hardware or software, or in a combination of hardware and software, as described in the "Implementation Options" paragraph. ..

Although some embodiments have been described in the context of the device, it is clear that these embodiments also represent a description of the corresponding method, the block or device corresponding to the function of the method step or method step. Similarly, the embodiments described in the context of a method step also represent a description of the corresponding block, item or function of the corresponding device. Some or all method steps can be performed by (or with) hardware devices such as, for example, microprocessors, programmable computers or electronic circuits. In some embodiments, one or more of the most important method steps can be performed by such a device.

Depending on the particular implementation requirements, embodiments of the invention can be implemented in hardware or in software. The implementation has an electronically readable control signal stored on it and works (or can) with a computer system programmable to perform each method, digitally. It can be executed using a storage medium such as a floppy (registered trademark) disk, DVD, Blu-ray (registered trademark) disk, CD, ROM, PROM, EPROM, EPROM or flash memory. Therefore, the digital storage medium can be made computer readable.

Some embodiments of the present invention have electronically readable control signals that can work with a programmable computer system so that one of the methods described herein is performed. Equipped with a data carrier.

In general, embodiments of the present invention can be implemented as a computer program product with program code capable of operating to perform one of the methods when the computer program product operates on a computer. The program code can be stored, for example, in a machine-readable carrier.

Another embodiment comprises a computer program stored in a machine-readable carrier that performs one of the methods described herein.

In other words, one embodiment of the method of the invention is therefore a computer program having program code that, when the computer program runs on a computer, performs one of the methods described herein.

A further embodiment of the method of the invention is therefore a data carrier (or digital storage medium or computer readable medium) comprising a computer program recorded on it and performing one of the methods described herein. ). Data carriers, digital storage media or recording media are usually tangible and / or non-volatile.

A further embodiment of the method of the invention is therefore a sequence of data streams or signals representing a computer program performing one of the methods described herein. A data stream or sequence of signals can be configured to be transferred, for example, by a data communication connection, such as the Internet.

Further embodiments include processing means configured or adapted to perform one of the methods described herein, such as a computer or programmable logic device.

A further embodiment comprises a computer on which a computer program that performs one of the methods described herein is installed.

A further embodiment of the invention is an apparatus configured to transfer (eg, electronically or optically) to a receiver a computer program that performs one of the methods described herein. Equipped with a system. The receiver can be, for example, a computer, a mobile device, a memory device, or the like. The device or system may include, for example, a file server that transfers a computer program to the receiver.
In some embodiments, programmable logic devices (eg, field programmable gate arrays) can be used to perform some or all of the functions of the methods described herein. In some embodiments, the field programmable gate array can work with a microprocessor to perform one of the methods described herein. In general, the method is preferably performed by any hardware device.

The devices described herein may be implemented using hardware devices, using computers, or using a combination of hardware devices and computers.

The devices described herein or any component of the devices described herein may be at least partially implemented in hardware and / or software.

The methods described herein may be performed using hardware equipment, using a computer, or using a combination of hardware equipment and a computer.

The methods described herein or any component of the equipment described herein may be at least partially performed by hardware and / or software.

The embodiments described herein are merely described to the principles of the invention. Modifications and changes to the configurations and details described herein will be apparent to those of skill in the art. Accordingly, it is intended that the invention is limited only by the scope of the imminent claims and not by the particular details represented by the methods of description and description of embodiments herein.

Claims (134)

A device for decoding the block (10) of the conversion coefficient.
In the sequence of paths (60) that scans the position (12) of the conversion factor of the block (10) according to the scan order (62).
Using context-adaptive binary arithmetic decoding,
Flags (92, 96, 98, 104), each of which is one of a set of one or more flag types, and
Using variable length code,
Residual value,
Decrypt from the data stream,
Allow each flag and each residual value to be decoded for the position (50) of the conversion factor currently being scanned, and
For each conversion factor position in the coded set of conversion factor positions, at least one of the one or more flags and one residual value is consecutively decoded and the conversion currently being scanned. The initial value domain (90), where the absolute value of the quantization index for the position of the coefficient exists, is contiguous so as to include only the absolute value of the quantization index for the position of the currently scanned conversion factor. Here, each flag limits the value domain of the absolute value of the quantization index for the position of the currently scanned conversion factor and the quantum of the position of the currently scanned conversion factor. If the value domain of the absolute value of the index is limited to the first or second subpart divided into two and the residual value is decoded for the position of the currently scanned conversion factor. The residual value is the value domain when at least one flag has been decoded for the position of the currently scanned conversion factor, or said when the flag has not been decoded for the position of the currently scanned conversion factor. From the initial value domain (90), it is configured to uniquely indicate the absolute value of the quantization index for the position of the currently scanned conversion factor.
The device is
For the position of the current conversion factor, select one set of reconstruction levels from multiple reconstruction level sets (73) based on the state that the state transition assumes for the position of the current conversion factor (72). ), The quantization index is dequantized to the reconstruction level indicated by the set of reconstruction levels (74), and
The state transition assumed for the position of the current conversion factor due to the position of the conversion factor following the current conversion factor in the scan order, depending on the quantization index of the position of the current conversion factor. To update the above-mentioned state of (76),
By using state transitions according to the scan order,
A device configured to be continuously dequantized. The device of claim 1, wherein the state transition transition is configured to be performed between four different states. _{The first subsequent state (84 1} ) depends on the binary function (86) applied to the quantized index (80) at the position of the current conversion factor in updating the state of the state transition. and is configured to perform the update by determining between a second subsequent state (84 _2), wherein said first subsequent state and the second subsequent state said current transform coefficients The device of claim 1 or 2, which depends on said state of position. The device according to any one of claims 1 to 3, wherein the binary function produces said parity or zero. The plurality (50) reconstruction level sets (52) are configured to be parameterized by a predetermined quantization step size to derive information about the predetermined quantization step size from the data stream. The device according to any one of claims 1 to 4. Each of the plurality (50) reconstruction level sets (52) is a predetermined quantization that is constant with respect to the plurality (50) reconstruction level set (52) with respect to the position of the current conversion factor. The device according to any one of claims 1 to 5, which comprises an integral multiple of the step size. The number of the reconstruction level sets (52) among the plurality of (50) reconstruction level sets (52) is 2, and the plurality of reconstruction level sets are.
With a first reconstruction level set containing zeros and even multiples of the predetermined quantization step size,
With a second reconstruction level set containing zeros and odd multiples of the predetermined quantization step size,
The apparatus according to any one of claims 1 to 6. The decoder is
In the first pass of the sequence of paths
The flag limiting the value domain of the absolute value of the quantization index for the position of the first conversion factor is the position of the second conversion factor following the position of the first conversion factor in scan order (62). A pre-determined first flag type flag (92) and a pre-determined second flag type flag (92) to be decoded before the flag limiting the value domain of the absolute value of the quantization index. 96) decodes from the data stream, wherein said decoding of the second flag type flag with a predetermined, wherein the first path (60 _1), predetermined abort criteria the scan The decoding of the predetermined first flag type flag (92) performed to and to include the predetermined conversion factor position (112) that is satisfied for the first time in sequence (62). , The flag (92) of the predetermined first flag type executed beyond the predetermined conversion factor position (112) in the scan sequence (62) is the currently scanned conversion. The apparatus according to any one of claims 1 to 7, which indicates whether or not the quantization index of the coefficient is zero. The apparatus of claim 8, wherein the flag (96) of the predetermined second flag type indicates the parity of the quantized index for the currently scanned conversion factor. In the first pass (60 _1), conversion indicating that the quantization indices of transform coefficients, wherein the first predetermined flag type of the flag (92) is the currently scanned is nonzero 13. Equipment. It said predetermined abort criterion is related to whether more than a threshold number has been previously determined for the flag to be decoded in the first pass (60 _1), Apparatus according to claim 8. In the first pass (60 _1), wherein the quantization index for the position of the transform coefficients is currently being scanned, in terms of absolute value, whether it is assumed that the minimum value of the values in the domain The apparatus according to claim 8 to 11, wherein the flag (98) of the third predetermined flag type shown is also configured to be decoded. In the first pass (60 _1), said first predetermined flag type of the flag (92) indicates that the quantization index for conversion coefficient the currently scanned is nonzero 12. The device of claim 12, configured to decode the flag of the third predetermined flag type exclusively with respect to the position of the conversion factor and the position of the conversion factor thereafter. Wherein in the first pass (60 _1), wherein the flag of which the said first predetermined flag type that quantization index is non-zero for the position of the transform coefficients is currently being scanned (92) With respect to the position of the conversion coefficient indicated by and the position of the conversion coefficient thereafter, the flag (98) of the third predetermined flag type is added after the flag (96) of the second predetermined flag type. 13. The device of claim 13, configured to decode. Wherein in the first pass (60 _1), wherein the flag of which the said first predetermined flag type that quantization index is non-zero for the position of the transform coefficients is currently being scanned (92) With respect to the position of the conversion coefficient indicated by and the position of the conversion coefficient thereafter, the position of the conversion coefficient indicating that the flag (98) of the third predetermined flag type is larger than 1 is exclusively described above. 13. The apparatus of claim 13, configured to decode the flag (96) of a second predetermined flag type. It said first path (60 ₁₎ followed by a second pass (60 ₂₎ Oite, wherein the quantization index for the position of the transform coefficients is currently being scanned, in the first pass (60 ₁₎ It also decodes a fourth predetermined flag type flag (104) indicating whether or not it is assumed to be the minimum value in the value domain with respect to the absolute value so as to be limited by the flag to be decoded. The apparatus according to any one of claims 8 to 15, which is configured as described above. 16. The apparatus of claim 16, wherein the residual value is configured to be decoded in one or more additional paths following the second path. In one or more passes following the first pass (60 _3, 60 _4), configured to decode the residual values, according to claims 8 to 17. In the last pass (60 _5), configured to decode the sign of non-zero transform coefficients, according to claims 8 to 18. The device is
In the state transition
If the position of the current conversion factor precedes the position of the predetermined conversion factor (112) in the scan order or is equal to the position of the predetermined conversion factor (112).
Depending on the flag (96) of the second flag type at the position of the current conversion factor,
If the current conversion factor position follows the predetermined conversion factor position (112) in the scan order,
Depending on the flag (92) of the first flag type at the position of the current conversion factor,
It is configured to perform the update of the state of the state transition.
In the context-adaptive entropy decoding, the state transition precedes the predetermined conversion factor position (112), depending on the state assumed for the position of the currently scanned conversion factor. Configured to determine the context for decoding the flag of the predetermined first flag type for the currently scanned conversion factor for the position of the containing and subsequent conversion factors. The device according to any one of claims 8 to 19. The device is
In the context-adaptive entropy decoding, the position of the conversion coefficient preceding and including the predetermined conversion coefficient position (112) is assumed to be the position of the conversion coefficient whose state transition is currently scanned. Depends on the state, and for the position of the conversion factor following the predetermined position of the conversion factor (112), the state transition is assumed for the position of the conversion factor currently being scanned. 8 is independently configured to determine the context for decoding the predetermined first flag type flag (92) with respect to the position of the currently scanned conversion factor. The device according to any one of 19. The decoder is
In the context-adaptive entropy decoding, the state transition precedes the predetermined conversion factor position (112), depending on the state assumed for the position of the currently scanned conversion factor. Determines the context for decoding the predetermined first flag type flag (92) for the position of the currently scanned conversion factor for the position of the conversion factor including and thereafter. Configured to
In the state transition, depending on the flag (92) of the first flag type at the position of the current conversion coefficient, the conversion coefficient following the position of each conversion coefficient in the scan order. The apparatus according to any one of claims 8 to 19, configured to perform the update of the state of the state transition assumed for the position of the current conversion factor with respect to the position. A device for decoding blocks of conversion factors,
In sequence (60 ₁ -60 ₅₎ of the path to be scanned in the scan order positions of the transform coefficients,
Using context-adaptive binary arithmetic decoding,
Flags (92, 96, 98, 104), each of which is one of a set of one or more flag types, and
Using variable-length code (the variable-length codeword bin is decoded in the non-adaptive bypass mode of the binary arithmetic decoder),
Residual value,
Decrypt from the data stream
Allow each flag and each residual value to be decoded for the position (50) of the conversion factor currently being scanned, and
For each conversion factor position in the coded set of conversion factor positions, at least one of the one or more flags and one residual value is consecutively decoded and the conversion currently being scanned. The initial value domain (90), where the absolute value of the quantization index for the position of the coefficient (50) is present, should include only the absolute value of the quantization index for the position of the currently scanned conversion factor. Continuously limiting, where each flag is the absolute value domain of the quantization index for the position of the currently scanned conversion factor, for the position of the currently scanned conversion factor. The value domain of the absolute value of the quantization index was limited to the first or second subpart divided into two, and the residual value was decoded for the position of the currently scanned conversion factor. If, the residual value is flagged for the value domain or for the position of the currently scanned conversion factor when at least one flag has been decoded for the position of the currently scanned conversion factor. If not, it is configured to uniquely indicate the absolute value of the quantization index for the position of the currently scanned conversion factor from the initial value domain.
The device is
In a first pass (60 ₁₎ of the sequence of the path,
Wherein from the data stream, the first flag type flag with a predetermined (92), in said first path (60 _1), the abort criterion which is previously determined is satisfied for the first time in the scan order (62), The flag (92) of the predetermined first flag type is configured to decode up to (and include) the position of the predetermined conversion factor (112), and the flag (92) of the predetermined first flag type is currently being scanned. Indicates whether or not the quantization index for the position (50) of the conversion factor is zero.
Decoding only the flag for the position of the conversion factor up to (and including) the predetermined conversion factor position (112) and in another path (60 _3,4 ) of the sequence of the path. Of the residual values, for each of the coded sets of the conversion coefficient positions after (and excluding) the predetermined conversion coefficient positions (112) in the scan order (62). An apparatus configured to decode one so that the latter uniquely indicates the absolute value of the quantized index with respect to the position of each of the conversion factors in the initial value domain (90). The decoder is
For the position of the current conversion factor, select one set of reconstruction levels from multiple reconstruction level sets (73) based on the state that the state transition assumes for the position of the current conversion factor (72). ), The quantization index is dequantized to the reconstruction level indicated by the set of reconstruction levels (74), and
The state transition assumed for the position of the current conversion factor due to the position of the conversion factor following the current conversion factor in the scan order, depending on the quantization index of the position of the current conversion factor. To update the above-mentioned state of (76),
23. The apparatus of claim 23, configured to continuously dequantize using state transitions according to said scan order. 24. The device of claim 24, configured to perform the transition of said state transition between four different states. _{The first subsequent state (84 1} ) depends on the binary function (86) applied to the quantized index (80) at the position of the current conversion factor in updating the state of the state transition. and is configured to perform the update by determining between a second subsequent state (84 _2), wherein said first subsequent state and the second subsequent state said current transform coefficients 25. The device of claim 24 or 25, which depends on said state of position. 25. The apparatus of any of claims 24 to 26, wherein the binary function yields the parity or zero. The plurality (50) reconstruction level sets (52) are configured to be parameterized by a predetermined quantization step size to derive information about the predetermined quantization step size from the data stream. The device according to any one of claims 24 to 27. Each of the plurality (50) reconstruction level sets (52) is a predetermined quantization that is constant with respect to the plurality (50) reconstruction level set (52) with respect to the position of the current conversion factor. The device according to any one of claims 24 to 28, which comprises an integral multiple of the step size. The number of the reconstruction level sets (52) among the plurality of (50) reconstruction level sets (52) is 2, and the plurality of reconstruction level sets are.
With a first reconstruction level set containing zeros and even multiples of the predetermined quantization step size,
With a second reconstruction level set containing zeros and odd multiples of the predetermined quantization step size,
24. The apparatus according to any one of claims 24 to 29. Abort criteria said predetermined is related to whether more than a threshold number has been previously determined for the flag to be decoded in the first pass (60 _1), in any one of claims 23 to 30 The device described. In the first pass (60 _1), wherein the quantization index for the position of the transform coefficients is currently being scanned, in terms of absolute value, whether it is assumed that the minimum value of the values in the domain The device according to any one of claims 23 to 31, wherein the flag (98) of the third predetermined flag type shown is also configured to be decoded. In the first pass (60 _1), said first predetermined flag type of the flag (92) indicates that the quantization index for conversion coefficient the currently scanned is nonzero 32. The apparatus of claim 32, configured to decode the flag of the third predetermined flag type exclusively for the position of the conversion factor and the position of the conversion factor thereafter. In the first pass (60 _1), said first predetermined flag type of the flag (92) indicates that the quantization index for conversion coefficient the currently scanned is nonzero For the position of the conversion factor and the position of the conversion factor thereafter, the flag (98) of the third predetermined flag type is decoded after the flag (96) of the second predetermined flag type. 33. The apparatus of claim 33, wherein said flag of the second predetermined flag type configured indicates said parity of the currently scanned conversion factor. Wherein in the first pass (60 _1), the flag of which the first predetermined flag type that the quantization index is non-zero for the position of the transform coefficients the currently scanned (92) With respect to the position of the conversion coefficient indicated by and the position of the conversion coefficient thereafter, the position of the conversion coefficient indicating that the flag (98) of the third predetermined flag type is larger than 1 is exclusively described above. 33. The apparatus of claim 33, configured to decode the flag (96) of the second predetermined flag type indicating the parity of the conversion factor currently being scanned. It said first path (60 ₁₎ followed by a second pass (60 ₂₎ Oite, wherein the quantization index for the position of the transform coefficients is currently being scanned, in the first pass (60 ₁₎ It also decodes a fourth predetermined flag type flag (104) indicating whether or not it is assumed to be the minimum value in the value domain with respect to the absolute value so as to be limited by the flag to be decoded. 23. The apparatus according to any one of claims 23 to 35. The apparatus according to any one of claims 1 to 36, which is configured to decode the variable length code bin in a non-adaptive bypass mode. Whether the position of the currently scanned conversion factor precedes the position of the predetermined conversion factor in the scanning order, or is the position of the predetermined conversion factor, or the position of the predetermined conversion factor. The variable length code is derived from a predefined set of variable length codes in order to differently decode the residual value for the position of the currently scanned conversion factor, depending on whether or not it follows the position of. The device according to any one of claims 1 to 37, which is configured to be selected. If the position of the currently scanned conversion factor precedes the position of the predetermined conversion factor (112) or is equal to the position of the predetermined conversion factor (112).
To decode the residual value for the position of the currently scanned conversion factor.
By gradually changing the parameter indicating the selected variable length code to the quantized index at the position of the preceding conversion factor that meets a predetermined criterion, and / or.
Depending on the quantization index of the conversion factor position near the currently scanned conversion factor position,
The apparatus according to any one of claims 1 to 38, wherein the variable length code is configured to select the variable length code from a predefined set of variable length codes. If the currently scanned conversion factor position follows the predetermined conversion factor position in the scan order.
To decode the residual value for the position of the currently scanned conversion factor.
Depending on the quantization index of the conversion factor position near the currently scanned conversion factor position, and.
Depending on the state in which the state transition assumes for the position of the currently scanned conversion factor,
The apparatus according to any one of claims 1 to 39, wherein the variable length code is configured to select the variable length code from a predefined and parameterized set of variable length codes. The decoder is
For the position of the current conversion factor, one set of reconstruction levels is selected from multiple reconstruction level sets based on the state that the state transition assumes for the position of the current conversion factor, and the quantized index. To dequantize the quantization index to the reconstruction level indicated by in the set of reconstruction levels, and
Depends on the quantization index for the position of the current conversion factor, it is assumed for the position of the current conversion factor due to the position of the conversion factor following the position of the current conversion factor in the scan order. Updating the state of the state transition,
23. 40. The apparatus of any of claims 23-40, configured to continuously dequantize using said state transitions according to said scan order. For each of the above sets of one or more flag types,
To decode the flag of each of the flag types in one of the sequences of the paths.
The device according to any one of claims 1 to 41, which is configured to perform the decoding. The apparatus according to any one of claims 1 to 42, wherein the variable length code is selected from a predefined set of variable length codes and a single parameter uniquely identifies one variable length code. 43. The apparatus of claim 43, wherein the predefined set of variable length codes is a set of Golomb rice codes. The device deciphers the residual value for the position of the currently scanned conversion factor.
Gradually changing the parameter indicating the selected variable length code to the quantized index at the position of the preceding conversion factor that meets a predetermined criterion, and / or.
Dependence on the quantization index of the conversion coefficient position near the currently scanned conversion coefficient position,
The apparatus according to any one of claims 1 to 44, wherein the variable length code is configured to select the variable length code from a predefined set of variable length codes. The encoded set of conversion factor positions that extend according to the scan order between said position (64) of the first nonzero quantization index in the scan order and the position of the predefined conversion factor (66). Decide,
The apparatus according to any one of claims 1 to 45, which is configured to identify the position of the first non-zero quantized index based on the data stream. The apparatus according to any one of claims 1 to 46, wherein for each non-zero quantization index, the sign bit is configured to be decoded from the data stream using an equal probability bypass mode. The flag (92) of the first flag type for a predetermined conversion factor position.
The apparatus according to any one of claims 1 to 47, configured to decode using context-adaptive entropy decoding by selecting a context depending on the coefficient position of the predetermined conversion factor. .. The flag of the predetermined flag type of the predetermined conversion coefficient position for a set of neighborhood conversion coefficient positions in the local template (52) around the predetermined conversion coefficient position (50). Determining local activity based on the set of flags decrypted prior to (92), and
Choosing a context depending on the local activity,
1. The flag (92) of the first predetermined flag type for the position of the predetermined conversion factor is configured to be decoded using context-adaptive entropy decoding. The device according to any of 48. The set of flags includes the flag (92) of the predetermined first flag type decoded for the set of positions of conversion coefficients in the vicinity and the predetermined second flag type. The device comprises the flag (96) and the flag (98) of the predetermined third flag type, wherein the device is based on the sum of the additions for each of the positions of the conversion factors in the vicinity. Configured to calculate activity, the addition is predetermined with said flag (92) of the predetermined first flag type decoded for the position of the conversion factor in the neighborhood. The quantization index for the position of the conversion factor in the vicinity, determined based on the flag (96) of the second flag type and the flag (98) of the predetermined third flag type. 49. The apparatus of claim 49, which indicates the minimum assumed absolute value, or the minimum assumed absolute reconstruction level of. The decoder is
For the position of each conversion factor, one reconstruction level set is selected from multiple reconstruction level sets based on the state that the state transition assumes for the position of each conversion coefficient, and the quantization index is Dequantizing the quantization index to the reconstruction level pointed to in the reconstruction level set, and
The state transition assumed for the position of the current conversion factor due to the position of the conversion factor following the current conversion factor in the scan order, depending on the quantization index of the position of the current conversion factor. To update the above state of
Is configured to continuously dequantize using state transitions according to the scan order.
The flag of the first flag type with respect to the position of the predetermined conversion factor,
The state and / or the state in which the state transition assumes the position of the predetermined conversion factor.
Claimed to be configured to decode using context-adaptive entropy decoding by selecting a context depending on said set of reconstruction levels selected for the position of the predetermined transformation factor. The device according to any one of 1 to 50. The flag (92) of the second flag type for a predetermined conversion factor position,
The apparatus according to any one of claims 1 to 51, which is configured to decode using context-adaptive entropy decoding by selecting a context depending on the coefficient position of the predetermined conversion coefficient. The second predetermined flag type of the predetermined conversion coefficient position for a set of nearby conversion coefficient positions in the local template (52) around the predetermined conversion coefficient position. Based on the set of flags decrypted before the flags, the local activity and / or the non-zero quantized index in the local template (52) around the position of the predetermined conversion factor. Determining the number of coefficients and
Choosing a context depending on the number of the local activity and / or the non-zero quantization index,
The flag (96) of the second predetermined flag type for the position of the predetermined conversion factor is configured to be decoded using context-adaptive entropy decoding. The device according to any one of 1 to 52. 53. The apparatus of claim 53, configured to select the context depending on the difference between the local activity and the number of non-zero quantized indexes. The set of flags includes the flag (92) of the predetermined first flag type decoded for the set of positions of conversion coefficients in the vicinity and the predetermined second flag type. The device comprises the flag (96) and the flag (98) of the predetermined third flag type, wherein the device is based on the sum of the additions for each of the positions of the conversion factors in the vicinity. Configured to calculate activity, the addition is predetermined with said flag (92) of the predetermined first flag type decoded for the position of the conversion factor in the neighborhood. The quantum about the position (51) of the conversion factor in the neighborhood determined based on the flag (96) of the second flag type and the flag (98) of the predetermined third flag type. The device of claim 52 or 53, which indicates the minimum assumed absolute value of the index or the minimum assumed absolute reconstruction level. The flag (98) of the third flag type for a predetermined conversion factor position.
The apparatus according to any one of claims 1 to 55, which is configured to decode using context-adaptive entropy decoding by selecting a context depending on the coefficient position of the predetermined conversion coefficient. Before the flag of the third predetermined flag type of the predetermined conversion factor for a set of neighborhood conversion factor positions in the local template around the predetermined conversion factor position. Based on the set of decoded flags, determine the number of conversion coefficients with a non-zero quantization index in the local template around the location of the local activity and / or the predetermined conversion factor. That, and
Choosing a context depending on the number of the local activity and / or the non-zero quantization index,
1. The flag (98) of the third predetermined flag type for the position of the predetermined conversion factor is configured to be decoded using context-adaptive entropy decoding. The device according to any one of 56 to 56. 58. The device of claim 57, configured to select the context depending on the difference between the local activity and the number of non-zero quantized indexes. The set of flags includes the flag of the predetermined first flag type decoded for the set of positions of conversion coefficients in the vicinity and the flag of the predetermined second flag type. , The device is configured to calculate the activity based on the sum of the additions for each of the positions of the conversion factors in the vicinity, including said flag of the predetermined third flag type. The addition is determined by the flag of the predetermined first flag type decoded for the position of the conversion factor in the vicinity, the flag of the predetermined second flag type, and the predetermined flag. A claim that indicates the minimum assumed absolute value for the quantization index or the minimum assumed absolute reconstruction level for the position of the conversion factor in the neighborhood determined based on the flag of the third flag type. 57 or 58. A decoder for decoding the conversion coefficient block (10).
For each of at least one set of the sub-blocks (14) into which the conversion factor block (10) is divided, the absolute value of the quantization index is predetermined for each of the sub-blocks (14). It also decodes the subblock critical flag indicating whether it contains a conversion factor (12) greater than the non-zero threshold.
Within each subblock (14) indicated by the subblock severity flag that there is at least one conversion factor whose absolute value of the quantized index is greater than the predetermined non-zero threshold.
For each of the conversion factors in each of the subblocks
The value domain of each of the conversion coefficients is inductively divided into two parts, and one or more flags indicating which of the two parts the quantized index of each conversion coefficient is located in. Decoding the sequence continuously, and stopping decoding the sequence as soon as the value domain contains only one value or an absolutely equal value, and
If the value domain still contains one or more values that differ in the absolute sense, by continuously decoding the residual value indicating the absolute value of the quantized index of each of the conversion coefficients in the value domain. , As well as
Within each subblock indicated by the subblock severity flag that there is no conversion factor whose absolute value of the quantized index is greater than the predetermined non-zero threshold.
For each of the conversion factors in each of the subblocks
When the sequence of one or more flags is continuously decoded and the value domain contains only one value that does not exceed the non-zero threshold, only one value or simply an absolutely equal value. By immediately stopping decoding of the sequence
A decoder configured to decode the conversion factor of the conversion factor block. 60. The apparatus of claim 60, wherein the first flag in the sequence of flags is a significant flag indicating whether or not the conversion factor from which the first flag is decoded is zero. The predetermined non-zero threshold is 1 and
The device is
Within each subblock indicated by the subblock severity flag that there is no conversion factor for which the absolute value of the quantized index is greater than 1.
For each of the conversion factors in each of the subblocks
16. The apparatus of claim 61, configured to continuously decode the first flag. For each of at least one other set of the subblocks in which the conversion factor blocks are divided, another subblock critical flag indicating whether each of the subblocks contains a conversion factor that is not equal to zero. Decrypt and
Determining the set of subblocks that make up the subblock indicated by the other subblock critical flag that the first subblock critical flag is decoded and contains at least one conversion factor that is not equal to zero.
Within each subblock indicated by the other subblock critical flag that there is no nonzero conversion factor
The apparatus according to any one of claims 60 to 62, wherein the conversion coefficients of the conversion coefficient block are configured to be estimated to be all zero. A device for encoding a block (10) of conversion coefficients.
In the sequence of paths (60) that scans the position (12) of the conversion factor of the block (10) according to the scan order (62).
Using context-adaptive binary arithmetic coding,
Flags (92, 96, 98, 104), each of which is one of a set of one or more flag types, and
Using variable length code,
Residual value,
Encoded into a data stream,
Each flag and each residual value is coded for the position (50) of the conversion factor currently being scanned, and
For each conversion factor position in the coded set of conversion factor positions, at least one of the one or more flags and one residual value is consecutively encoded and is currently being scanned. The initial value domain (90), where the absolute value of the quantization index for the position of the coefficient exists, is contiguous so as to include only the absolute value of the quantization index for the position of the currently scanned conversion factor. Here, each flag limits the value domain of the absolute value of the quantization index for the position of the currently scanned conversion factor and the quantum of the position of the currently scanned conversion factor. The absolute value domain of the conversion index was restricted to the first or second subpart divided into two, and the residual value was encoded for the position of the currently scanned conversion factor. If the residual value is encoded for the value domain when at least one flag is encoded for the position of the currently scanned conversion factor, or for the position of the currently scanned conversion factor. When not, the initial value domain (90) is configured to uniquely indicate the absolute value of the quantization index for the position of the currently scanned conversion factor.
The device is
For the position of the current conversion factor, one reconstruction level set is selected from the plurality of reconstruction level sets (73) based on the state that the state transition assumes for the position of the current conversion factor (72). The conversion factor for the position of the current conversion factor is inversely quantized from the selected set of reconstruction levels into a quantization index that uniquely indicates the reconstruction level (74).
The state transition assumed for the position of the current conversion factor due to the position of the conversion factor following the current conversion factor in the scan order, depending on the quantization index of the position of the current conversion factor. To update the above-mentioned state of (76),
By using state transitions according to the scan order,
A device configured to be continuously dequantized. 64. The apparatus of claim 64, configured to perform the transition of said state transition between four different states. _{The first subsequent state (84 1} ) depends on the binary function (86) applied to the quantized index (80) at the position of the current conversion factor in updating the state of the state transition. and is configured to perform the update by determining between a second subsequent state (84 _2), wherein said first subsequent state and the second subsequent state said current transform coefficients The device of claim 63 or 65, which depends on said state of position. The device of any of claims 63-66, wherein the binary function yields the parity or zero. A claim configured to parameterize the plurality (50) reconstruction level sets (52) with a predetermined quantization step size and write information about the predetermined quantization step size to the data stream. Item 6. The apparatus according to any one of items 63 to 67. Each of the plurality (50) reconstruction level sets (52) is a predetermined quantization that is constant with respect to the plurality (50) reconstruction level set (52) with respect to the position of the current conversion factor. The apparatus according to any one of claims 63 to 68, which comprises an integral multiple of the step size. The number of the reconstruction level sets (52) among the plurality of (50) reconstruction level sets (52) is 2, and the plurality of reconstruction level sets are.
With a first reconstruction level set containing zeros and even multiples of the predetermined quantization step size,
With a second reconstruction level set containing zeros and odd multiples of the predetermined quantization step size,
The device according to any one of claims 63 to 69. The encoder is
In the first pass of the sequence of paths
The flag limiting the value domain of the absolute value of the quantization index for the position of the first conversion factor is the position of the second conversion factor following the position of the first conversion factor in scan order (62). The data includes a predetermined first flag type flag and a predetermined second flag type flag to be encoded before the flag limiting the value domain of the absolute value of the quantization index. encoded in the stream, wherein the encoding of the second flag type flag said predetermined, the first pass in (60 _1), the abort criterion which is previously determined the scan order (62) The coding of the predetermined first flag type flag (92) performed to and to include the predetermined conversion factor position (112) that is satisfied for the first time in the scan. The flag (92) of the predetermined first flag type is the said flag (92) of the currently scanned conversion factor executed beyond the position (112) of the predetermined conversion factor in sequence (62). The apparatus according to any one of claims 64 to 70, which indicates whether or not the quantization index is zero. 17. The apparatus of claim 71, wherein the flag (96) of the predetermined second flag type indicates the parity of the quantized index for the currently scanned conversion factor. In the first pass (60 _1), conversion indicating that the quantization indices of transform coefficients, wherein the first predetermined flag type of the flag (92) is the currently scanned is nonzero One of claims 71 or 72 configured to encode said flag (96) of the second predetermined flag type exclusively with respect to the position of the coefficient and the position of the subsequent conversion factor. The device described. 17. The apparatus of claim 71, wherein the predetermined abort criteria relates to whether the number of the flags encoded in the _{first pass (601) exceeds a predetermined threshold.} In the first pass (60 _1), wherein the quantization index for the position of the transform coefficients is currently being scanned, in terms of absolute value, whether it is assumed that the minimum value of the values in the domain 17. The apparatus of claim 71-74, wherein the flag (98) of the third predetermined flag type shown is also configured to encode. In the first pass (60 _1), said first predetermined flag type of the flag (92) indicates that the quantization index for conversion coefficient the currently scanned is nonzero 25. The apparatus of claim 75, configured to encode the flag of the third predetermined flag type exclusively with respect to the position of the conversion factor and the position of the conversion factor thereafter. Wherein in the first pass (60 _1), wherein the flag of which the said first predetermined flag type that quantization index is non-zero for the position of the transform coefficients is currently being scanned (92) With respect to the position of the conversion coefficient indicated by and the position of the conversion coefficient thereafter, the flag (98) of the third predetermined flag type is added after the flag (96) of the second predetermined flag type. 36. The device of claim 76, configured to encode. Wherein in the first pass (60 _1), wherein the flag of which the said first predetermined flag type that quantization index is non-zero for the position of the transform coefficients is currently being scanned (92) With respect to the position of the conversion coefficient indicated by and the position of the conversion coefficient thereafter, the position of the conversion coefficient indicating that the flag (98) of the third predetermined flag type is larger than 1 is exclusively described above. 27. The apparatus of claim 76, configured to encode said flag (96) of a second predetermined flag type. Said first path (60 ₁₎ followed by a second pass (60 ₂₎ Oite that, the quantization index for the position of the transform coefficients the currently scanned, the minimum value of the values in the domain the as limited by the flag being encoded in the first pass (60 _1), in terms of absolute value, the fourth predetermined flag type flags indicating whether to assume (104) the sign The device according to any one of claims 71 to 78, which is configured to be the same. 39. The device of claim 79, configured to encode the residual value in one or more additional paths following the second path. In one or more passes following the first pass (60 _3, 60 _4), wherein configured to encode the residual value, according to claim 71 to 78. At the end of the path, and the reference numeral (60 ₅₎ of non-zero transform coefficients to encode, according to claim 71 to 81. The encoder is
In the state transition
If the position of the current conversion factor precedes the position of the predetermined conversion factor (112) in the scan order or is equal to the position of the predetermined conversion factor (112).
Depending on the flag (96) of the second flag type at the position of the current conversion factor,
If the current conversion factor position follows the predetermined conversion factor position (112) in the scan order,
Depending on the flag (92) of the first flag type at the position of the current conversion factor,
It is configured to perform the update of the state of the state transition.
In the context-adaptive entropy coding, the state transition precedes the predetermined conversion factor position (112), depending on the state assumed for the position of the currently scanned conversion factor. To determine the context for encoding the flag of the predetermined first flag type for the currently scanned conversion factor for the position of the conversion factor including and thereafter. The apparatus according to any one of claims 71 to 82. The device is
In the context-adaptive entropy coding, the position of the conversion factor preceding and including the predetermined conversion factor position (112) is assumed to be the position of the conversion factor whose state transition is currently scanned. Depends on said state, and for the position of the conversion factor following the predetermined position of the conversion factor (112), said state that the state transition assumes for the position of the conversion factor currently being scanned. Independently of the claims, it is configured to determine the context for encoding the flag (92) of the predetermined first flag type with respect to the position of the currently scanned conversion factor. Item 7. The apparatus according to any one of Items 71 to 82. The encoder is
In the context-adaptive entropy coding, the state transition precedes the predetermined conversion factor position (112), depending on the state assumed for the position of the currently scanned conversion factor. Context for encoding the predetermined first flag type flag (92) for the currently scanned conversion factor position for and for all subsequent conversion factor positions. Is configured to determine
In the state transition, depending on the flag (92) of the first flag type at the position of the current conversion coefficient, the conversion coefficient following the position of each conversion coefficient in the scan order. 23. The apparatus of any of claims 71-82, configured to perform said update of said state of said state transition assumed for the position of said current conversion factor with respect to position. A device for encoding blocks of conversion coefficients,
In sequence (60 ₁ -60 ₅₎ of the path to be scanned in the scan order positions of the transform coefficients,
Using context-adaptive binary arithmetic coding,
Flags (92, 96, 98, 104), each of which is one of a set of one or more flag types, and
Using variable length code,
Residual value,
Encoded from the data stream
Each flag and each residual value is coded for the position (50) of the conversion factor currently being scanned, and
At least one of the one or more flags and one residual value is continuously encoded and currently scanned for the position of each conversion factor in the coded set of conversion factor positions. The initial value domain (90) where the absolute value of the quantization index for the position of the conversion factor (50) is present should include only the absolute value of the quantization index for the position of the conversion factor currently being scanned. Each flag is continuously limited to the absolute value domain of the quantization index for the position of the currently scanned conversion factor, for the position of the currently scanned conversion factor. The value domain of the absolute value of the quantization index is limited to the first or second subpart divided into two, and the residual value is encoded for the position of the currently scanned conversion factor. If so, the residual value is flagged for the value domain when at least one flag is encoded for the position of the currently scanned conversion factor, or for the position of the currently scanned conversion factor. When not, it is configured to uniquely indicate the absolute value of the quantization index for the position of the currently scanned conversion factor from the initial value domain.
The device is
In a first pass (60 ₁₎ of the sequence of the path,
Predetermined first flag type flag (92) converting, in said first path (60 _1), the predetermined abort criterion is met for the first time in the scan order (62), which is predetermined The flag (92) of the predetermined first flag type is configured to encode to the data stream up to the coefficient position (112) with respect to the currently scanned conversion coefficient position (50). Indicates whether the quantization index of is zero or not.
Only the flag for the position of the conversion factor up to (and including) the predetermined conversion factor position (112) is encoded and in another path (60 _3,4 ) of the sequence of the path. , One of the residual values is encoded for each of the coded sets of the conversion coefficient positions after the predetermined conversion coefficient position in the scan order (62), the latter being the initial. A device configured to uniquely indicate the absolute value of the quantization index for the position of each of the conversion coefficients in the value domain (90). The device is
For the position of the current conversion factor, one reconstruction level set is selected from the plurality of reconstruction level sets (73) based on the state that the state transition assumes for the position of the current conversion factor (72). To dequantize the quantization index to the reconstruction level indicated by the quantization index in the set of reconstruction levels (74), and.
The state transition assumed for the position of the current conversion factor due to the position of the conversion factor following the current conversion factor in the scan order, depending on the quantization index of the position of the current conversion factor. To update the above-mentioned state of (76),
By using state transitions according to the scan order,
The apparatus of claim 86, configured to be continuously dequantized. 87. The apparatus of claim 87, configured to perform the transition of said state transition between four different states. _{The first subsequent state (84 1} ) depends on the binary function (86) applied to the quantized index (80) at the position of the current conversion factor in updating the state of the state transition. and is configured to perform the update by determining between a second subsequent state (84 _2), wherein said first subsequent state and the second subsequent state said current transform coefficients 8. The device of claim 87 or 88, which depends on said state of position. The device of any of claims 87-89, wherein the binary function yields the parity or zero. The plurality (50) reconstruction level sets (52) are configured to be parameterized by a predetermined quantization step size to derive information about the predetermined quantization step size from the data stream. The device according to any one of claims 87 to 90. Each of the plurality (50) reconstruction level sets (52) is a predetermined quantization that is constant with respect to the plurality (50) reconstruction level set (52) with respect to the position of the current conversion factor. The apparatus according to any one of claims 87 to 91, which comprises an integral multiple of the step size. The number of the reconstruction level sets (52) among the plurality of (50) reconstruction level sets (52) is 2, and the plurality of reconstruction level sets are.
With a first reconstruction level set containing zeros and even multiples of the predetermined quantization step size,
With a second reconstruction level set containing zeros and odd multiples of the predetermined quantization step size,
The apparatus according to any one of claims 87 to 92. 46. The apparatus of claim 86, wherein the predetermined abort criteria relates to whether the number of the flags encoded in the _{first pass (601) exceeds a predetermined threshold.} In the first pass (60 _1), wherein the quantization index for the position of the transform coefficients is currently being scanned, in terms of absolute value, whether it is assumed that the minimum value of the values in the domain 46. The apparatus of claim 86-94, wherein the flag (98) of the third predetermined flag type shown is also configured to encode. In the first pass (60 _1), said first predetermined flag type of the flag (92) indicates that the quantization index for conversion coefficient the currently scanned is nonzero 95. The apparatus of claim 95, configured to encode the flag of the third predetermined flag type exclusively with respect to the position of the conversion factor and the position of the conversion factor thereafter. Wherein in the first pass (60 _1), wherein the flag of which the said first predetermined flag type that quantization index is non-zero for the position of the transform coefficients is currently being scanned (92) With respect to the position of the conversion coefficient indicated by and the position of the conversion coefficient thereafter, the flag (98) of the third predetermined flag type is added after the flag (96) of the second predetermined flag type. 9. The apparatus of claim 96, wherein said flag of the second predetermined flag type, configured to encode, indicates said parity of the currently scanned conversion factor. Wherein in the first pass (60 _1), wherein the flag of which the said first predetermined flag type that quantization index is non-zero for the position of the transform coefficients is currently being scanned (92) With respect to the position of the conversion coefficient indicated by and the position of the conversion coefficient thereafter, the position of the conversion coefficient indicating that the flag (98) of the third predetermined flag type is larger than 1 is exclusively described above. 19. The apparatus of claim 96, configured to encode the flag (96) of the second predetermined flag type indicating the parity of the conversion factor currently being scanned. It said first path (60 ₁₎ followed by a second pass (60 ₂₎ Oite, wherein the quantization index for the position of the transform coefficients is currently being scanned, in the first pass (60 ₁₎ A fourth predetermined flag type flag (104) indicating whether or not to assume the minimum value in the value domain with respect to the absolute value is also coded so as to be limited by the encoded flag. The apparatus according to any one of claims 86 to 98, which is configured to be the same. The apparatus according to any one of claims 1 to 99, configured to encode the variable length code bin in a non-adaptive bypass mode. Whether the position of the currently scanned conversion factor precedes the position of the predetermined conversion factor in the scanning order, or is the position of the predetermined conversion factor, or the position of the predetermined conversion factor. From a predefined and parameterized set of variable length codes to differently encode the residual value for the position of the currently scanned conversion factor, depending on whether or not it follows the position of. 46. The device of claim 86 or 94, configured to select a variable length code. If the position of the currently scanned conversion factor precedes the position of the predetermined conversion factor (112) or is equal to the position of the predetermined conversion factor (112).
To encode the residual value for the position of the currently scanned conversion factor.
By gradually changing the parameter indicating the selected variable length code to the quantized index at the position of the preceding conversion factor that meets a predetermined criterion, and / or.
Depending on the quantization index of the conversion factor position near the currently scanned conversion factor position,
The device of any of claims 86 or 94 or 101, configured to select said variable length code from a predefined and parameterized set of variable length code. If the currently scanned conversion factor position follows the predetermined conversion factor position in the scan order.
To encode the residual value for the position of the currently scanned conversion factor.
Depending on the quantization index of the conversion factor position near the currently scanned conversion factor position, and.
Depending on the state in which the state transition assumes for the position of the currently scanned conversion factor,
The device of any of claims 86 or 94 or 101 or 102, configured to select said variable length code from a predefined and parameterized set of variable length code. The device is
For the position of the current conversion factor, one reconstruction level set is selected from multiple reconstruction level sets and the selected rearrangement is selected based on the state that the state transition assumes for the current conversion factor position. To dequantize the conversion factor for the position of the current conversion factor into a quantization index that uniquely indicates the reconstruction level from the set of construction levels, and
The state assumed for the position of the current conversion factor due to the position of the conversion factor following the current conversion factor in the scan order, depending on the quantization index for the position of the current conversion factor. Updating the said state of the transition,
By using state transitions according to the scan order,
The apparatus according to any one of claims 86 to 103, which is configured to be continuously dequantized. For each of the above sets of one or more flag types,
To encode the flag of each of the flag types in one of the sequences of the paths.
The device according to any one of claims 64 to 85 or 86 to 104, configured to perform the coding. The apparatus according to any one of claims 1 to 105, wherein the variable length code is selected from a predefined and parameterized set of variable length codes, wherein a single parameter uniquely identifies one variable length code. The device of claim 106, wherein the predefined set of variable length codes is a set of Golomb rice codes. The device encodes the residual value for the position of the currently scanned conversion factor.
Gradually changing the parameter indicating the selected variable length code to the quantized index at the position of the preceding conversion factor that meets a predetermined criterion, and / or.
Dependence on the quantization index of the conversion coefficient position near the currently scanned conversion coefficient position,
The apparatus according to any one of claims 1 to 107, wherein the variable length code is configured to select the variable length code from a predefined set of variable length codes. The encoded set of conversion factor positions that extend according to the scan order between said position (64) of the first nonzero quantization index in the scan order and the position of the predefined conversion factor (66). Decide,
The apparatus according to any one of claims 1 to 108, wherein the data stream is configured to encode said position of the first non-zero quantized index. The apparatus according to any one of claims 1 to 109, wherein for each non-zero quantization index, the sign bit is configured to encode the sign bit into the data stream using an equal probability bypass mode. The flag (92) of the first flag type for a predetermined conversion factor position.
13. Equipment. The flag of the predetermined flag type of the predetermined conversion coefficient position for a set of neighborhood conversion coefficient positions in the local template (52) around the predetermined conversion coefficient position (50). Determining local activity based on the set of flags encoded prior to (92), and
Choosing a context depending on the local activity,
The flag (92) of the first predetermined flag type for the position of the predetermined conversion factor is configured to be encoded using context-adaptive entropy coding. The device according to any one of 1 to 111. The set of flags is the flag (92) of the predetermined first flag type encoded for the set of positions of conversion coefficients in the vicinity and the predetermined second flag type. The flag (96) and the flag (98) of the predetermined third flag type are included, and the device is based on the sum of the additions for each of the positions of the conversion factors in the vicinity. The addition is configured to calculate the activity and is predetermined with the flag (92) of the predetermined first flag type encoded for the position of the conversion factor in the neighborhood. The quantum with respect to the position of the conversion factor in the vicinity, determined based on the flag (96) of the second flag type and the flag (98) of the predetermined third flag type. 12. The device of claim 112, which indicates the minimum assumed absolute value of the index, or the minimum assumed absolute reconstruction level. The encoder is
For each transformation coefficient position, one reconstruction level set is selected from multiple reconstruction level sets and the selected reconstruction is selected based on the state that the state transition assumes for each transformation coefficient position. To dequantize the conversion factor for the position of the current conversion factor into a quantization index that uniquely indicates the reconstruction level from the set of construction levels, and
The state transition assumed for the position of the current conversion factor due to the position of the conversion factor following the current conversion factor in the scan order, depending on the quantization index of the position of the current conversion factor. To update the above state of
Is configured to continuously dequantize using state transitions according to the scan order.
The flag of the first flag type with respect to the position of the predetermined conversion factor,
The state and / or the state in which the state transition assumes the position of the predetermined conversion factor.
Configured to encode using context-adaptive entropy coding by selecting a context depending on said set of reconstruction levels selected for the position of the predetermined transformation factor. The device according to any one of claims 1 to 113. The flag (92) of the second flag type for a predetermined conversion factor position,
13. Device. The second predetermined flag type of the predetermined conversion coefficient position for a set of nearby conversion coefficient positions in the local template (52) around the predetermined conversion coefficient position. Based on the set of flags encoded before the flags, the local activity and / or the quantization index in the local template (52) around the position of the predetermined conversion factor is not zero. Determining the number of conversion coefficients, and
Choosing a context depending on the number of the local activity and / or the non-zero quantization index,
Is configured to encode the flag (96) of the second predetermined flag type for the position of the predetermined conversion factor using context-adaptive entropy coding. The device according to any one of claims 1 to 115. 11. The device of claim 116, configured to select the context depending on the difference between the local activity and the number of non-zero quantized indexes. The set of flags is the flag (92) of the predetermined first flag type encoded for the set of positions of conversion coefficients in the vicinity and the predetermined second flag type. The flag (96) and the flag (98) of the predetermined third flag type are included, and the device is based on the sum of the additions for each of the positions of the conversion factors in the vicinity. The addition is configured to calculate the activity and is predetermined with the flag (92) of the predetermined first flag type encoded for the position of the conversion factor in the neighborhood. Regarding the position (51) of the conversion coefficient in the vicinity determined based on the flag (96) of the second flag type and the flag (98) of the predetermined third flag type. The apparatus according to claim 115 or 116, which indicates the minimum assumed absolute value of the quantization index or the minimum assumed absolute reconstruction level. The flag (98) of the third flag type for a predetermined conversion factor position.
13. Device. Before the flag of the third predetermined flag type of the predetermined conversion coefficient position for a set of nearby conversion coefficient positions in the local template around the predetermined conversion coefficient position. Determines the number of conversion coefficients whose quantization index is non-zero in the local template around the location of the local activity and / or the predetermined conversion factor based on a set of flags encoded by. To do and
Choosing a context depending on the number of the local activity and / or the non-zero quantization index,
Is configured to encode the flag (98) of the third predetermined flag type for the position of the predetermined conversion factor using context-adaptive entropy coding. The device according to any one of claims 1 to 119. 120. The apparatus of claim 120, configured to select the context depending on the difference between the local activity and the number of non-zero quantized indexes. The set of flags is the flag of the predetermined first flag type encoded for the set of positions of the conversion coefficients in the vicinity and the flag of the predetermined second flag type. And the flag of the predetermined third flag type, the device is configured to calculate the activity based on the sum of the additions for each of the positions of the conversion coefficients in the neighborhood. , The addition is the flag of the predetermined first flag type encoded for the position of the conversion factor in the neighborhood and the flag of the predetermined second flag type. Indicates the minimum assumed absolute value of the quantization index or the minimum assumed absolute reconstruction level for the position of the conversion factor in the neighborhood determined based on the flag of the predetermined third flag type. The device according to claim 119 or 120. An encoder for encoding the conversion coefficient block (10).
For each of at least one set of the sub-blocks (14) into which the conversion factor block (10) is divided, the absolute value of the quantization index is predetermined for each of the sub-blocks (14). It also encodes a subblock critical flag indicating whether it contains a conversion factor (12) greater than the non-zero threshold.
Within each subblock (14) indicated by the subblock severity flag that there is at least one conversion factor whose absolute value of the quantized index is greater than the predetermined non-zero threshold.
For each of the conversion factors in each of the subblocks
The value domain of each of the conversion coefficients is inductively divided into two parts, and one or more flags indicating which of the two parts the quantized index of each conversion coefficient is located in. Encoding the sequence continuously, and stopping the encoding of the sequence as soon as the value domain contains only one value or a value that is absolutely equal, and
If the value domain still contains one or more values that differ in the absolute sense, the residual value indicating the absolute value of the quantization index of each of the conversion coefficients in the value domain is continuously encoded. , As well as
Within each subblock indicated by the subblock severity flag that there is no conversion factor whose absolute value of the quantized index is greater than the predetermined non-zero threshold.
For each of the conversion factors in each of the subblocks
The sequence of one or more flags is continuously encoded, and the value domain contains only one value that does not exceed the non-zero threshold, only one value or simply an absolutely equal value. By stopping the coding of the sequence as soon as possible
An encoder configured to encode the conversion factor of the conversion factor block. 23. The apparatus of claim 123, wherein the first flag in the sequence of flags is a significant flag indicating whether or not the conversion factor in which the first flag is encoded is zero. The predetermined non-zero threshold is 1 and
The device is
Within each subblock indicated by the subblock severity flag that there is no conversion factor for which the absolute value of the quantized index is greater than 1.
For each of the conversion factors in each of the subblocks
The device according to claim 124, which is configured to continuously encode the first flag. For each of at least one other set of the subblocks in which the conversion factor blocks are divided, another subblock critical flag indicating whether each of the subblocks contains a conversion factor that is not equal to zero. Encoded
Determining the set of subblocks that make up the subblock indicated by the other subblock critical flag that the first subblock critical flag is encoded and contains at least one conversion factor that is not equal to zero.
Within each subblock indicated by the other subblock critical flags, the decoder indicates that there is no nonzero conversion factor.
The apparatus according to any one of claims 123 to 125, wherein the conversion coefficients of the conversion coefficient block are configured so that they can be estimated to be all zero. It is a method for decoding the block (10) of the conversion coefficient.
In the sequence of paths (60) that scans the position (12) of the conversion factor of the block (10) according to the scan order (62).
Using the context-adaptive binary arithmetic compound,
Flags (92, 96, 98, 104), each of which is one of a set of one or more flag types, and
Using variable length code,
Residual value,
The step of decrypting from the data stream
Each flag and each residual value is decoded at the position (50) of the conversion factor currently being scanned, and
For each conversion factor position in the coded set of conversion factor positions, at least one of the one or more flags and one residual value is consecutively decoded and the conversion currently being scanned. The initial value domain (90), where the absolute value of the quantization index for the position of the coefficient exists, is contiguous so as to include only the absolute value of the quantization index for the position of the currently scanned conversion factor. Here, each flag limits the value domain of the absolute value of the quantization index for the position of the currently scanned conversion factor and the quantum of the position of the currently scanned conversion factor. If the absolute value domain of the index is limited to the first or second subpart divided into two and the residual value is decoded for the position of the currently scanned conversion factor, the residual. The value is the value domain when at least one flag for the position of the currently scanned conversion factor has been decoded, or said initial when the flag for the position of the currently scanned conversion factor has not been decoded. Includes a step from the value domain (90) that uniquely indicates the absolute value of the quantization index for the position of the currently scanned conversion factor.
The method is
For the position of the current conversion factor, select one set of reconstruction levels from multiple reconstruction level sets (73) based on the state that the state transition assumes for the position of the current conversion factor (72). ), The quantization index is dequantized to the reconstruction level indicated by the set of reconstruction levels (74), and
The state transition assumed for the position of the current conversion factor due to the position of the conversion factor following the current conversion factor in the scan order, depending on the quantization index of the position of the current conversion factor. To update the above-mentioned state of (76),
By using state transitions according to the scan order,
A method that includes steps of continuous dequantization. A method for decoding blocks of conversion factors,
In sequence (60 ₁ -60 ₅₎ of the path to be scanned in the scan order positions of the transform coefficients,
Using context-adaptive binary arithmetic decoding,
Flags (92, 96, 98, 104), each of which is one of a set of one or more flag types, and
Using variable-length code (the bin of the variable-length codeword is decoded in the non-adaptive bypass mode of the binary arithmetic decoder),
Residual value,
A step of decoding from the data stream.
Each flag and each residual value is decoded at the position (50) of the conversion factor currently being scanned, and
For each conversion factor position in the coded set of conversion factor positions, at least one of the one or more flags and one residual value is consecutively decoded and the conversion currently being scanned. The initial value domain (90), where the absolute value of the quantization index for the position of the coefficient (50) is present, should include only the absolute value of the quantization index for the position of the currently scanned conversion factor. Continuously limiting, where each flag is the absolute value domain of the quantization index for the position of the currently scanned conversion factor, for the position of the currently scanned conversion factor. The value domain of the absolute value of the quantization index was limited to the first or second subpart divided into two, and the residual value was decoded for the position of the currently scanned conversion factor. If, the residual value is flagged for the value domain or for the position of the currently scanned conversion factor when at least one flag has been decoded for the position of the currently scanned conversion factor. If not, it comprises a step from the initial value domain that uniquely indicates the absolute value of the quantization index for the position of the currently scanned conversion factor.
The method is
In a first pass (60 ₁₎ of the sequence of the path,
In the first pass (60 _1), predetermined abort criterion is met for the first time in the scan order (62), the position of the predetermined conversion coefficient to (112) (and, contains it) A step of decoding a predetermined first flag type flag (92) from the data stream, wherein the predetermined first flag type flag (92) is the currently scanned conversion. A step indicating whether or not the quantization index for the position (50) of the coefficient is zero, and
Decoding only the flags up to (and including) the position of the conversion factor to (and including) the predetermined conversion factor position and scanning order in _{another path 60 3,4) of the sequence of said paths.} For each of the coded sets of positions of the conversion coefficients after (and excluding) the predetermined conversion coefficient positions (112) of (62), one of the residual values. A method comprising decoding so that the latter uniquely indicates the absolute value of the quantized index with respect to the position of each of the conversion coefficients in the initial value domain (90). A method for decoding the conversion coefficient block (10).
For each of at least one set of the sub-blocks (14) into which the conversion factor block (10) is divided, the absolute value of the quantization index is predetermined for each of the sub-blocks (14). A step of decoding a subblock critical flag indicating whether or not it contains a conversion factor (12) greater than the non-zero threshold.
Within each subblock (14) indicated by the subblock severity flag that there is at least one conversion factor whose absolute value of the quantized index is greater than the predetermined non-zero threshold.
For each of the conversion factors in each of the subblocks
The value domain of each of the conversion coefficients is inductively divided into two parts, and one or more flags indicating which of the two parts the quantized index of each conversion coefficient is located in. Decoding the sequence continuously, and stopping decoding the sequence as soon as the value domain contains only one value or an absolutely equal value, and
If the value domain still contains one or more values that differ in the absolute sense, the residual value indicating the absolute value of the quantization index of each of the conversion coefficients in the value domain is continuously decoded. And,
Within each subblock indicated by the subblock severity flag that there is no conversion factor whose absolute value of the quantized index is greater than the predetermined non-zero threshold.
For each of the conversion factors in each of the subblocks
When the sequence of one or more flags is continuously decoded and the value domain contains only one value that does not exceed the non-zero threshold, only one value or simply an absolutely equal value. By immediately stopping decoding of the sequence
A method comprising decoding the conversion factor of the conversion factor block. A method for encoding a block (10) of conversion coefficients.
In the sequence of paths (60) that scans the position (12) of the conversion factor of the block (10) according to the scan order (62).
Using context-adaptive binary arithmetic coding,
Flags (92, 96, 98, 104), each of which is one of a set of one or more flag types, and
Using variable length code,
Residual value,
A step to encode from a data stream
Each flag and each residual value is coded for the position (50) of the conversion factor currently being scanned, and
At least one of the one or more flags and one residual value is continuously encoded and currently scanned for each conversion factor position in the coded set of conversion factor positions. The initial value domain (90) in which the absolute value of the quantization index for the position of the conversion factor is present is continuous to include only the absolute value of the quantization index for the position of the conversion factor currently being scanned. Here, each flag limits the value domain of the absolute value of the quantization index to the position of the currently scanned conversion factor to the position of the currently scanned conversion factor. When the value domain of the absolute value of the quantization index is limited to the first or second subpart divided into two and the residual value is encoded for the position of the currently scanned conversion factor. , The residual value is flagged for the value domain when at least one flag is encoded for the position of the currently scanned conversion factor, or for the position of the currently scanned conversion factor. When not, it comprises a step from the initial value domain (90) that uniquely indicates the absolute value of the quantization index for the position of the currently scanned conversion factor.
The method is
For the position of the current conversion factor, one reconstruction level set is selected from the plurality of reconstruction level sets (73) based on the state that the state transition assumes for the position of the current conversion factor (72). The conversion factor for the position of the current conversion factor is inversely quantized from the selected set of reconstruction levels into a quantization index that uniquely indicates the reconstruction level (74).
The state transition assumed for the position of the current conversion factor due to the position of the conversion factor following the current conversion factor in the scan order, depending on the quantization index of the position of the current conversion factor. To update the above-mentioned state of (76),
By using state transitions according to the scan order,
A method involving steps of continuous dequantization. A method for encoding blocks of conversion coefficients,
In sequence (60 ₁ -60 ₅₎ of the path to be scanned in the scan order positions of the transform coefficients,
Using context-adaptive binary arithmetic coding,
Flags (92, 96, 98, 104), each of which is one of a set of one or more flag types, and
Using variable length code,
Residual value,
A step of encoding from the data stream.
Each flag and each residual value is coded for the position (50) of the conversion factor currently being scanned, and
At least one of the one or more flags and one residual value is continuously encoded and currently scanned for each conversion factor position in the coded set of conversion factor positions. The initial value domain (90) where the absolute value of the quantization index for the position of the conversion factor (50) is present should include only the absolute value of the quantization index for the position of the conversion factor currently being scanned. Each flag is continuously limited to, where the value domain of the absolute value of the quantization index with respect to the position of the currently scanned conversion factor is the position of the currently scanned conversion factor. The value domain of the absolute value of the quantization index for is limited to the first or second subpart divided into two and the residual value is encoded for the position of the currently scanned conversion factor. If so, the residual value is flagged for the value domain when at least one flag for the position of the currently scanned conversion factor is encoded, or for the position of the currently scanned conversion factor. Includes a step that uniquely indicates the absolute value of the quantization index for the position of the currently scanned conversion factor from the initial value domain when unencoded.
The method is
In a first pass (60 ₁₎ of the sequence of the path,
The first flag type flag with a predetermined (92), wherein in the first pass (60 _1), satisfies the first time predetermined abort criterion in the scan order (62), transform coefficients previously determined In the step of encoding to the data stream up to the position (112), the predetermined first flag type flag (92) is for the currently scanned conversion factor position (50). A step indicating whether or not the quantization index is zero,
Only the flag for the position of the conversion factor up to (and including) the predetermined conversion factor position (112) is encoded and the scan order in _{another path (60 3,4) of the sequence of said paths.} For each of the coded sets of the conversion coefficient positions after the predetermined conversion coefficient position (112) in (62), one of the residual values is encoded, the latter being the initial. A method comprising the step of uniquely indicating the absolute value of the quantized index for the position of each of the conversion coefficients in the value domain (90). A method for encoding the conversion factor block (10).
For each of at least one set of the sub-blocks (14) into which the conversion factor block (10) is divided, the absolute value of the quantization index is predetermined for each of the sub-blocks (14). A step of encoding a subblock critical flag indicating whether or not it contains a conversion factor (12) greater than the non-zero threshold.
Within each subblock (14) indicated by the subblock severity flag that there is at least one conversion factor whose absolute value of the quantized index is greater than the predetermined non-zero threshold.
For each of the conversion factors in each of the subblocks
The value domain of each of the conversion coefficients is inductively divided into two parts, and one or more flags indicating which of the two parts the quantized index of each conversion coefficient is located in. Encoding the sequence continuously, and stopping the encoding of the sequence as soon as the value domain contains only one value or a value that is absolutely equal, and
If the value domain still contains one or more values that differ in the absolute sense, the residual value indicating the absolute value of the quantization index of each of the conversion coefficients in the value domain is continuously encoded. , As well as
Within each subblock indicated by the subblock severity flag that there is no conversion factor whose absolute value of the quantized index is greater than the predetermined non-zero threshold.
For each of the conversion factors in each of the subblocks
The sequence of one or more flags is continuously encoded, and the value domain contains only one value that does not exceed the non-zero threshold, only one value or simply an absolutely equal value. By stopping the coding of the sequence as soon as possible
A method comprising encoding the conversion factor of the conversion factor block. A data stream encoded by the method according to any one of claims 130 to 132. A computer program comprising program code for performing the method according to any one of claims 127 to 132 while running on a computer.

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